diff --git a/01-rstudio-intro.html b/01-rstudio-intro.html
index 63a0eb87b..a62d537b1 100644
--- a/01-rstudio-intro.html
+++ b/01-rstudio-intro.html
@@ -930,7 +930,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1210,7 +1210,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb64">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1264,7 +1264,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1303,7 +1303,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1334,7 +1334,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
@@ -1436,7 +1436,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/01-rstudio-intro.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/02-project-intro.html b/02-project-intro.html
index 9163d6631..fc24de508 100644
--- a/02-project-intro.html
+++ b/02-project-intro.html
@@ -787,7 +787,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/02-project-intro.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/03-seeking-help.html b/03-seeking-help.html
index fc353dd4c..47541de05 100644
--- a/03-seeking-help.html
+++ b/03-seeking-help.html
@@ -596,7 +596,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The <code>c()</code> function creates a vector, in which all elements
 are of the same type. In the first case, the elements are numeric, in
@@ -625,7 +625,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>To look at the help for the <code>paste()</code> function, use:</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -733,7 +733,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The standard R function for reading tab-delimited files with a period
 decimal separator is read.delim(). You can also do this with
@@ -822,7 +822,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/03-seeking-help.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/04-data-structures-part1.html b/04-data-structures-part1.html
index aa5a39aa6..37661b3ad 100644
--- a/04-data-structures-part1.html
+++ b/04-data-structures-part1.html
@@ -816,7 +816,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -1041,7 +1041,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Tip 1.1</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -1073,7 +1073,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Tip 1.2</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -1112,7 +1112,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -1125,7 +1125,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul><li>Weight is expressed on a continuous scale (real numbers). The R data
 type for this is “double” (also known as “numeric”).</li>
@@ -1157,7 +1157,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -1195,7 +1195,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -1385,7 +1385,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1609,7 +1609,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -1652,7 +1652,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Solution to Challenge 4</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -1840,7 +1840,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2100,7 +2100,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -2144,7 +2144,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -2184,7 +2184,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2234,7 +2234,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
@@ -2334,7 +2334,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/04-data-structures-part1.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/05-data-structures-part2.html b/05-data-structures-part2.html
index 0845dbee3..a808561a0 100644
--- a/05-data-structures-part2.html
+++ b/05-data-structures-part2.html
@@ -1147,7 +1147,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/05-data-structures-part2.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/06-data-subsetting.html b/06-data-subsetting.html
index b4c8ed67b..bba05df9e 100644
--- a/06-data-subsetting.html
+++ b/06-data-subsetting.html
@@ -694,7 +694,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -881,7 +881,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1134,7 +1134,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul><li>The <strong>wrong</strong> way to do this problem is
 <code>countries==seAsia</code>. This gives a warning
@@ -1415,7 +1415,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -1560,7 +1560,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1624,7 +1624,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1778,7 +1778,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal"><li>Extract observations collected for the year 1957</li>
@@ -1850,7 +1850,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li><p><code>gapminder</code> is a data.frame so needs to be subsetted
 on two dimensions. <code>gapminder[1:20, ]</code> subsets the data to
@@ -1943,7 +1943,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/06-data-subsetting.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/07-control-flow.html b/07-control-flow.html
index 0f114b1ab..3061e045f 100644
--- a/07-control-flow.html
+++ b/07-control-flow.html
@@ -1203,7 +1203,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/07-control-flow.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/08-plot-ggplot2.html b/08-plot-ggplot2.html
index 96cae79d1..143818711 100644
--- a/08-plot-ggplot2.html
+++ b/08-plot-ggplot2.html
@@ -494,7 +494,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Here is one possible solution:</p>
 <div class="codewrapper sourceCode" id="cb5">
@@ -533,7 +533,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>The solution presented below adds <code>color=continent</code> to the
 call of the <code>aes</code> function. The general trend seems to
@@ -643,7 +643,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The lines now get drawn over the points!</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -773,7 +773,7 @@ <h3 class="callout-title">Challenge 4a<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4a</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>Here a possible solution: Notice that the <code>color</code> argument
 is supplied outside of the <code>aes()</code> function. This means that
@@ -815,7 +815,7 @@ <h3 class="callout-title">Challenge 4b<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 4b</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Here is a possible solution: Notice that supplying the
 <code>color</code> argument inside the <code>aes()</code> functions
@@ -967,7 +967,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Here a possible solution: <code>xlab()</code> and <code>ylab()</code>
 set labels for the x and y axes, respectively The axis title, text and
@@ -1061,7 +1061,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/08-plot-ggplot2.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/09-vectorization.html b/09-vectorization.html
index 2df294357..908e70aa9 100644
--- a/09-vectorization.html
+++ b/09-vectorization.html
@@ -466,7 +466,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Let’s try this on the <code>pop</code> column of the
 <code>gapminder</code> dataset.</p>
@@ -516,7 +516,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Refresh your plotting skills by plotting population in millions
 against year.</p>
@@ -693,7 +693,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Given the following matrix:</p>
 <div class="codewrapper sourceCode" id="cb28">
@@ -770,7 +770,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We’re interested in looking at the sum of the following sequence of
 fractions:</p>
@@ -980,7 +980,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/09-vectorization.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/10-functions.html b/10-functions.html
index 7c8cf70c4..6aa59ecd1 100644
--- a/10-functions.html
+++ b/10-functions.html
@@ -523,7 +523,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Write a function called <code>kelvin_to_celsius</code> that takes a
 temperature in Kelvin and returns that temperature in Celsius</p>
@@ -579,7 +579,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Define the function to convert directly from Fahrenheit to Celsius,
 by reusing these two functions above</p>
@@ -711,7 +711,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Extend our previous definition of the function by adding in an
 explicit call to <code>stopifnot()</code>. Since
@@ -967,7 +967,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1024,7 +1024,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Write a function called <code>fence()</code> that takes two vectors
 as arguments, called <code>text</code> and <code>wrapper</code>, and
@@ -1179,7 +1179,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/10-functions.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/11-writing-data.html b/11-writing-data.html
index fef41c54c..9119dfd47 100644
--- a/11-writing-data.html
+++ b/11-writing-data.html
@@ -651,7 +651,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/11-writing-data.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/12-plyr.html b/12-plyr.html
index f3a73afde..c529be369 100644
--- a/12-plyr.html
+++ b/12-plyr.html
@@ -563,7 +563,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -793,7 +793,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -893,7 +893,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Alternative Challenge</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>Answer 3 will calculate the average life expectancy per
 continent.</p>
@@ -973,7 +973,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/12-plyr.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/13-dplyr.html b/13-dplyr.html
index 0e46882d9..27a667739 100644
--- a/13-dplyr.html
+++ b/13-dplyr.html
@@ -605,7 +605,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -736,7 +736,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1098,7 +1098,7 @@ <h3 class="callout-title">Advanced Challenge<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Advanced Challenge</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb52">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1206,7 +1206,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/13-dplyr.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/14-tidyr.html b/14-tidyr.html
index a302dac19..25339396e 100644
--- a/14-tidyr.html
+++ b/14-tidyr.html
@@ -464,7 +464,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The original gapminder data.frame is in an intermediate format. It is
 not purely long since it had multiple observation variables
@@ -656,7 +656,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -952,7 +952,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1126,7 +1126,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/14-tidyr.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/15-knitr-markdown.html b/15-knitr-markdown.html
index b342e0d6e..101fd89f4 100644
--- a/15-knitr-markdown.html
+++ b/15-knitr-markdown.html
@@ -899,7 +899,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/15-knitr-markdown.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/16-wrap-up.html b/16-wrap-up.html
index 5c25a3abb..f075b5f4c 100644
--- a/16-wrap-up.html
+++ b/16-wrap-up.html
@@ -555,7 +555,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/16-wrap-up.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/404.html b/404.html
index 01a368405..67e98223c 100644
--- a/404.html
+++ b/404.html
@@ -418,8 +418,8 @@ <h1>Page not found</h1>
   "url": "https://swcarpentry.github.io/r-novice-gapminder/404.html",
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/404.html",
   "dateCreated": "2015-04-18",
-  "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "dateModified": "2024-01-09",
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/CODE_OF_CONDUCT.html b/CODE_OF_CONDUCT.html
index bbb0ef656..af50ac98c 100644
--- a/CODE_OF_CONDUCT.html
+++ b/CODE_OF_CONDUCT.html
@@ -418,7 +418,7 @@ <h1>Contributor Code of Conduct</h1>
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/CODE_OF_CONDUCT.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/LICENSE.html b/LICENSE.html
index 0d7c8717e..ba41256d7 100644
--- a/LICENSE.html
+++ b/LICENSE.html
@@ -469,7 +469,7 @@ <h1>Licenses</h1>
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/LICENSE.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/aio.html b/aio.html
index 908dc9ab6..ac2acb570 100644
--- a/aio.html
+++ b/aio.html
@@ -1015,7 +1015,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1300,7 +1300,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb64">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1354,7 +1354,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1393,7 +1393,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1424,7 +1424,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
@@ -2124,7 +2124,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The <code>c()</code> function creates a vector, in which all elements
 are of the same type. In the first case, the elements are numeric, in
@@ -2153,7 +2153,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>To look at the help for the <code>paste()</code> function, use:</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -2261,7 +2261,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The standard R function for reading tab-delimited files with a period
 decimal separator is read.delim(). You can also do this with
@@ -2766,7 +2766,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -2996,7 +2996,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Tip 1.1</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -3029,7 +3029,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Tip 1.2</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -3071,7 +3071,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -3084,7 +3084,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul>
 <li>Weight is expressed on a continuous scale (real numbers). The R data
@@ -3118,7 +3118,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -3157,7 +3157,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -3348,7 +3348,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3578,7 +3578,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -3623,7 +3623,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Solution to Challenge 4</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -3814,7 +3814,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4075,7 +4075,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -4119,7 +4119,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -4161,7 +4161,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4213,7 +4213,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
@@ -5347,7 +5347,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5540,7 +5540,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5795,7 +5795,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul>
 <li>The <strong>wrong</strong> way to do this problem is
@@ -6086,7 +6086,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -6232,7 +6232,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6296,7 +6296,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6461,7 +6461,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal">
@@ -6545,7 +6545,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li><p><code>gapminder</code> is a data.frame so needs to be subsetted
@@ -7526,7 +7526,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Here is one possible solution:</p>
 <div class="codewrapper sourceCode" id="cb5">
@@ -7566,7 +7566,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>The solution presented below adds <code>color=continent</code> to the
 call of the <code>aes</code> function. The general trend seems to
@@ -7678,7 +7678,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The lines now get drawn over the points!</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -7810,7 +7810,7 @@ <h3 class="callout-title">Challenge 4a<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4a</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>Here a possible solution: Notice that the <code>color</code> argument
 is supplied outside of the <code>aes()</code> function. This means that
@@ -7853,7 +7853,7 @@ <h3 class="callout-title">Challenge 4b<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 4b</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Here is a possible solution: Notice that supplying the
 <code>color</code> argument inside the <code>aes()</code> functions
@@ -8011,7 +8011,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Here a possible solution: <code>xlab()</code> and <code>ylab()</code>
 set labels for the x and y axes, respectively The axis title, text and
@@ -8173,7 +8173,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Let’s try this on the <code>pop</code> column of the
 <code>gapminder</code> dataset.</p>
@@ -8223,7 +8223,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Refresh your plotting skills by plotting population in millions
 against year.</p>
@@ -8403,7 +8403,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Given the following matrix:</p>
 <div class="codewrapper sourceCode" id="cb28">
@@ -8486,7 +8486,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We’re interested in looking at the sum of the following sequence of
 fractions:</p>
@@ -8809,7 +8809,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Write a function called <code>kelvin_to_celsius</code> that takes a
 temperature in Kelvin and returns that temperature in Celsius</p>
@@ -8866,7 +8866,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Define the function to convert directly from Fahrenheit to Celsius,
 by reusing these two functions above</p>
@@ -9000,7 +9000,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Extend our previous definition of the function by adding in an
 explicit call to <code>stopifnot()</code>. Since
@@ -9259,7 +9259,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9316,7 +9316,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Write a function called <code>fence()</code> that takes two vectors
 as arguments, called <code>text</code> and <code>wrapper</code>, and
@@ -9883,7 +9883,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -10113,7 +10113,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -10217,7 +10217,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Alternative Challenge</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>Answer 3 will calculate the average life expectancy per
 continent.</p>
@@ -10492,7 +10492,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -10625,7 +10625,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -10991,7 +10991,7 @@ <h3 class="callout-title">Advanced Challenge<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Advanced Challenge</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb52">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -11160,7 +11160,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The original gapminder data.frame is in an intermediate format. It is
 not purely long since it had multiple observation variables
@@ -11353,7 +11353,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -11650,7 +11650,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -12474,8 +12474,8 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
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   "dateCreated": "2015-04-18",
-  "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "dateModified": "2024-01-09",
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diff --git a/discuss.html b/discuss.html
index f73d411d4..287214819 100644
--- a/discuss.html
+++ b/discuss.html
@@ -412,7 +412,7 @@ <h1>Discussion</h1>
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   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
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   </script><script>
diff --git a/images.html b/images.html
index 8f2bb608c..d028eae7a 100644
--- a/images.html
+++ b/images.html
@@ -613,8 +613,8 @@ <h3 id="15-knitr-markdown-figure-3">Figure 3</h3>
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   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/images.html",
   "dateCreated": "2015-04-18",
-  "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "dateModified": "2024-01-09",
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/index.html b/index.html
index 3f69e4840..2ea4dec92 100644
--- a/index.html
+++ b/index.html
@@ -431,8 +431,8 @@ <h3 class="callout-title">Prerequisites<a class="anchor" aria-label="anchor" hre
   "url": "https://swcarpentry.github.io/r-novice-gapminder/index.html",
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/index.html",
   "dateCreated": "2015-04-18",
-  "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "dateModified": "2024-01-09",
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor-notes.html b/instructor-notes.html
index 85b3082ea..88207f551 100644
--- a/instructor-notes.html
+++ b/instructor-notes.html
@@ -594,8 +594,8 @@ <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i
   "url": "https://swcarpentry.github.io/r-novice-gapminder/instructor-notes.html",
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor-notes.html",
   "dateCreated": "2015-04-18",
-  "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "dateModified": "2024-01-09",
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/01-rstudio-intro.html b/instructor/01-rstudio-intro.html
index b5179e7e5..08ad377f2 100644
--- a/instructor/01-rstudio-intro.html
+++ b/instructor/01-rstudio-intro.html
@@ -932,7 +932,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1212,7 +1212,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb64">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1266,7 +1266,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1305,7 +1305,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1336,7 +1336,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
@@ -1438,7 +1438,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/01-rstudio-intro.html",
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   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
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   </script><script>
diff --git a/instructor/02-project-intro.html b/instructor/02-project-intro.html
index 25a5f3b39..5938678c2 100644
--- a/instructor/02-project-intro.html
+++ b/instructor/02-project-intro.html
@@ -789,7 +789,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
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-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
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diff --git a/instructor/03-seeking-help.html b/instructor/03-seeking-help.html
index a846be0cc..aa6a4d4ea 100644
--- a/instructor/03-seeking-help.html
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@@ -598,7 +598,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The <code>c()</code> function creates a vector, in which all elements
 are of the same type. In the first case, the elements are numeric, in
@@ -627,7 +627,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>To look at the help for the <code>paste()</code> function, use:</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -735,7 +735,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The standard R function for reading tab-delimited files with a period
 decimal separator is read.delim(). You can also do this with
@@ -824,7 +824,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
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   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
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diff --git a/instructor/04-data-structures-part1.html b/instructor/04-data-structures-part1.html
index 8b935b1fb..959551a6f 100644
--- a/instructor/04-data-structures-part1.html
+++ b/instructor/04-data-structures-part1.html
@@ -818,7 +818,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -1043,7 +1043,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Tip 1.1</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -1075,7 +1075,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Tip 1.2</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -1114,7 +1114,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -1127,7 +1127,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul><li>Weight is expressed on a continuous scale (real numbers). The R data
 type for this is “double” (also known as “numeric”).</li>
@@ -1159,7 +1159,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -1197,7 +1197,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -1387,7 +1387,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1611,7 +1611,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Solution to Challenge 3</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -1654,7 +1654,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Solution to Challenge 4</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
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 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -1842,7 +1842,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2102,7 +2102,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -2146,7 +2146,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -2186,7 +2186,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2236,7 +2236,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
@@ -2336,7 +2336,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/04-data-structures-part1.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/05-data-structures-part2.html b/instructor/05-data-structures-part2.html
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--- a/instructor/05-data-structures-part2.html
+++ b/instructor/05-data-structures-part2.html
@@ -1149,7 +1149,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/05-data-structures-part2.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/06-data-subsetting.html b/instructor/06-data-subsetting.html
index 55fdd6b17..f7a447342 100644
--- a/instructor/06-data-subsetting.html
+++ b/instructor/06-data-subsetting.html
@@ -696,7 +696,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -883,7 +883,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1136,7 +1136,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul><li>The <strong>wrong</strong> way to do this problem is
 <code>countries==seAsia</code>. This gives a warning
@@ -1417,7 +1417,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -1562,7 +1562,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1626,7 +1626,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1780,7 +1780,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal"><li>Extract observations collected for the year 1957</li>
@@ -1852,7 +1852,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li><p><code>gapminder</code> is a data.frame so needs to be subsetted
 on two dimensions. <code>gapminder[1:20, ]</code> subsets the data to
@@ -1945,7 +1945,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/06-data-subsetting.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/07-control-flow.html b/instructor/07-control-flow.html
index 9628301b3..c8214c8bb 100644
--- a/instructor/07-control-flow.html
+++ b/instructor/07-control-flow.html
@@ -1205,7 +1205,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/07-control-flow.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/08-plot-ggplot2.html b/instructor/08-plot-ggplot2.html
index fc22c43ee..4c543c929 100644
--- a/instructor/08-plot-ggplot2.html
+++ b/instructor/08-plot-ggplot2.html
@@ -496,7 +496,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Here is one possible solution:</p>
 <div class="codewrapper sourceCode" id="cb5">
@@ -535,7 +535,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>The solution presented below adds <code>color=continent</code> to the
 call of the <code>aes</code> function. The general trend seems to
@@ -645,7 +645,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The lines now get drawn over the points!</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -775,7 +775,7 @@ <h3 class="callout-title">Challenge 4a<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4a</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>Here a possible solution: Notice that the <code>color</code> argument
 is supplied outside of the <code>aes()</code> function. This means that
@@ -817,7 +817,7 @@ <h3 class="callout-title">Challenge 4b<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 4b</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Here is a possible solution: Notice that supplying the
 <code>color</code> argument inside the <code>aes()</code> functions
@@ -969,7 +969,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Here a possible solution: <code>xlab()</code> and <code>ylab()</code>
 set labels for the x and y axes, respectively The axis title, text and
@@ -1063,7 +1063,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/08-plot-ggplot2.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/09-vectorization.html b/instructor/09-vectorization.html
index 251cfaa9e..2654652ba 100644
--- a/instructor/09-vectorization.html
+++ b/instructor/09-vectorization.html
@@ -468,7 +468,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Let’s try this on the <code>pop</code> column of the
 <code>gapminder</code> dataset.</p>
@@ -518,7 +518,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Refresh your plotting skills by plotting population in millions
 against year.</p>
@@ -695,7 +695,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Given the following matrix:</p>
 <div class="codewrapper sourceCode" id="cb28">
@@ -772,7 +772,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We’re interested in looking at the sum of the following sequence of
 fractions:</p>
@@ -982,7 +982,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/09-vectorization.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/10-functions.html b/instructor/10-functions.html
index 51775a467..aa9bd2725 100644
--- a/instructor/10-functions.html
+++ b/instructor/10-functions.html
@@ -525,7 +525,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Write a function called <code>kelvin_to_celsius</code> that takes a
 temperature in Kelvin and returns that temperature in Celsius</p>
@@ -581,7 +581,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Define the function to convert directly from Fahrenheit to Celsius,
 by reusing these two functions above</p>
@@ -713,7 +713,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Extend our previous definition of the function by adding in an
 explicit call to <code>stopifnot()</code>. Since
@@ -969,7 +969,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1026,7 +1026,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Write a function called <code>fence()</code> that takes two vectors
 as arguments, called <code>text</code> and <code>wrapper</code>, and
@@ -1181,7 +1181,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/10-functions.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/11-writing-data.html b/instructor/11-writing-data.html
index 3d9d3bd88..d7cc6ee27 100644
--- a/instructor/11-writing-data.html
+++ b/instructor/11-writing-data.html
@@ -653,7 +653,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/r-novice-gapminder/instructor/11-writing-data.html",
   "dateCreated": "2015-04-18",
   "dateModified": "2024-01-04",
-  "datePublished": "2024-01-04"
+  "datePublished": "2024-01-09"
 }
 
   </script><script>
diff --git a/instructor/12-plyr.html b/instructor/12-plyr.html
index 39bcedef0..6012dd692 100644
--- a/instructor/12-plyr.html
+++ b/instructor/12-plyr.html
@@ -565,7 +565,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -795,7 +795,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -895,7 +895,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
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 <p>Answer 3 will calculate the average life expectancy per
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diff --git a/instructor/14-tidyr.html b/instructor/14-tidyr.html
index f992256fb..88f2140c1 100644
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 <p>The original gapminder data.frame is in an intermediate format. It is
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 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
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diff --git a/instructor/16-wrap-up.html b/instructor/16-wrap-up.html
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index 2f568d6e0..b40ec3f64 100644
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index 812793b36..4147f6365 100644
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diff --git a/instructor/LICENSE.html b/instructor/LICENSE.html
index 71ce6a42a..7c7925bb6 100644
--- a/instructor/LICENSE.html
+++ b/instructor/LICENSE.html
@@ -471,7 +471,7 @@ <h1>Licenses</h1>
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diff --git a/instructor/aio.html b/instructor/aio.html
index 943de0f77..2a57ee8d5 100644
--- a/instructor/aio.html
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@@ -1018,7 +1018,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
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 <div class="accordion-body">
 <p>The following can be used as R variables:</p>
 <div class="codewrapper sourceCode" id="cb44">
@@ -1303,7 +1303,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
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 <div class="codewrapper sourceCode" id="cb64">
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 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>One way of answering this question in R is to use the
 <code>&gt;</code> to set up the following:</p>
@@ -1396,7 +1396,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
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 </button>
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+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>We can use the <code>rm</code> command to accomplish this task</p>
 <div class="codewrapper sourceCode" id="cb70">
@@ -1427,7 +1427,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
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 </button>
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 <div class="accordion-body">
 <p>We can use the <code>install.packages()</code> command to install the
 required packages.</p>
@@ -2129,7 +2129,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
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 <div class="accordion-body">
 <p>The <code>c()</code> function creates a vector, in which all elements
 are of the same type. In the first case, the elements are numeric, in
@@ -2158,7 +2158,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
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 <div class="accordion-body">
 <p>To look at the help for the <code>paste()</code> function, use:</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -2266,7 +2266,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
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 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
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 <div class="accordion-body">
 <p>The standard R function for reading tab-delimited files with a period
 decimal separator is read.delim(). You can also do this with
@@ -2772,7 +2772,7 @@ <h3 class="callout-title">Discussion 1<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Discussion 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
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 <div class="accordion-body">
 <p>By keeping everything in a column the same, we allow ourselves to
 make simple assumptions about our data; if you can interpret one entry
@@ -3002,7 +3002,7 @@ <h4 id="print-the-data">1. Print the data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
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 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
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 <div class="accordion-body">
 <p>Show the content of any variable by typing its name.</p>
 <div class="section level3">
@@ -3035,7 +3035,7 @@ <h3 class="callout-title">2. Overview of the data types<a class="anchor" aria-la
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
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 </button>
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 <div class="accordion-body">
 <p>In the chapter “Data types” we saw two functions that can show data
 types. One printed just a single word, the data type name. The other
@@ -3077,7 +3077,7 @@ <h4 id="which-data-type-do-we-need">3. Which data type do we need?<a class="anch
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   <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>Scroll up to the section about the <a href="#the-type-hierarchy">type
 hierarchy</a> to review the available data types</p>
@@ -3090,7 +3090,7 @@ <h4 class="accordion-header" id="headingSolution4">Tip 1.3</h4>
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to Challenge 1.3</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <ul>
 <li>Weight is expressed on a continuous scale (real numbers). The R data
@@ -3124,7 +3124,7 @@ <h3 class="callout-title">4. Correct the problematic value<a class="anchor" aria
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Tip 1.4</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
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 <div class="accordion-body">
 <p>Revisit the hierarchy of data types when two different data types are
 combined.</p>
@@ -3163,7 +3163,7 @@ <h4 id="convert-the-column-weight-to-the-correct-data-type">5. Convert the colum
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Tip 1.5</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>The functions to convert data types start with <code>as.</code>. You
 can look for the function further up in the manuscript or use the
@@ -3354,7 +3354,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
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 </button>
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 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb92">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3584,7 +3584,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
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 </button>
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 <div class="accordion-body">
 <p>You get the names of an object by wrapping the object name inside
 <code>names(...)</code>. Similarly, you get the data type of the names
@@ -3629,7 +3629,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
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 </button>
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+<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
 <div class="accordion-body">
 <pre><code><span><span class="va">letter_no</span> <span class="op">&lt;-</span> <span class="fl">1</span><span class="op">:</span><span class="fl">26</span>   <span class="co"># or seq(1,26)</span></span>
 <span><span class="fu">names</span><span class="op">(</span><span class="va">letter_no</span><span class="op">)</span> <span class="op">&lt;-</span> <span class="va">LETTERS</span></span>
@@ -3820,7 +3820,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution11" aria-expanded="false" aria-controls="collapseSolution11">
   <h4 class="accordion-header" id="headingSolution11">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution11" class="accordion-collapse collapse" aria-labelledby="headingSolution11" data-bs-parent="#accordionSolution11">
+<div id="collapseSolution11" class="accordion-collapse collapse" data-bs-parent="#accordionSolution11" aria-labelledby="headingSolution11">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb138">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4081,7 +4081,7 @@ <h3 class="callout-title">Challenge 6<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution12" aria-expanded="false" aria-controls="collapseSolution12">
   <h4 class="accordion-header" id="headingSolution12">Solution to Challenge 6</h4>
 </button>
-<div id="collapseSolution12" class="accordion-collapse collapse" aria-labelledby="headingSolution12" data-bs-parent="#accordionSolution12">
+<div id="collapseSolution12" class="accordion-collapse collapse" data-bs-parent="#accordionSolution12" aria-labelledby="headingSolution12">
 <div class="accordion-body">
 <p>What do you think will be the result of
 <code>length(matrix_example)</code>?</p>
@@ -4125,7 +4125,7 @@ <h3 class="callout-title">Challenge 7<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution13" aria-expanded="false" aria-controls="collapseSolution13">
   <h4 class="accordion-header" id="headingSolution13">Solution to Challenge 7</h4>
 </button>
-<div id="collapseSolution13" class="accordion-collapse collapse" aria-labelledby="headingSolution13" data-bs-parent="#accordionSolution13">
+<div id="collapseSolution13" class="accordion-collapse collapse" data-bs-parent="#accordionSolution13" aria-labelledby="headingSolution13">
 <div class="accordion-body">
 <p>Make another matrix, this time containing the numbers 1:50, with 5
 columns and 10 rows. Did the <code>matrix</code> function fill your
@@ -4167,7 +4167,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution14" aria-expanded="false" aria-controls="collapseSolution14">
   <h4 class="accordion-header" id="headingSolution14">Solution to Challenge 8</h4>
 </button>
-<div id="collapseSolution14" class="accordion-collapse collapse" aria-labelledby="headingSolution14" data-bs-parent="#accordionSolution14">
+<div id="collapseSolution14" class="accordion-collapse collapse" data-bs-parent="#accordionSolution14" aria-labelledby="headingSolution14">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb173">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4219,7 +4219,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution15" aria-expanded="false" aria-controls="collapseSolution15">
   <h4 class="accordion-header" id="headingSolution15">Solution to Challenge 9</h4>
 </button>
-<div id="collapseSolution15" class="accordion-collapse collapse" aria-labelledby="headingSolution15" data-bs-parent="#accordionSolution15">
+<div id="collapseSolution15" class="accordion-collapse collapse" data-bs-parent="#accordionSolution15" aria-labelledby="headingSolution15">
 <div class="accordion-body">
 <p>Consider the R output of the matrix below:</p>
 <div class="codewrapper">
@@ -5355,7 +5355,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5548,7 +5548,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5803,7 +5803,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <ul>
 <li>The <strong>wrong</strong> way to do this problem is
@@ -6094,7 +6094,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>D</p>
 </div>
@@ -6240,7 +6240,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb115">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6304,7 +6304,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to challenge 6</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb122">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6469,7 +6469,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Solution to challenge 7</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
 <div class="accordion-body">
 <p>Fix each of the following common data frame subsetting errors:</p>
 <ol style="list-style-type: decimal">
@@ -6553,7 +6553,7 @@ <h3 class="callout-title">Challenge 8<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Solution to challenge 8</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li><p><code>gapminder</code> is a data.frame so needs to be subsetted
@@ -7536,7 +7536,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Here is one possible solution:</p>
 <div class="codewrapper sourceCode" id="cb5">
@@ -7576,7 +7576,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>The solution presented below adds <code>color=continent</code> to the
 call of the <code>aes</code> function. The general trend seems to
@@ -7688,7 +7688,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The lines now get drawn over the points!</p>
 <div class="codewrapper sourceCode" id="cb11">
@@ -7820,7 +7820,7 @@ <h3 class="callout-title">Challenge 4a<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4a</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>Here a possible solution: Notice that the <code>color</code> argument
 is supplied outside of the <code>aes()</code> function. This means that
@@ -7863,7 +7863,7 @@ <h3 class="callout-title">Challenge 4b<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 4b</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Here is a possible solution: Notice that supplying the
 <code>color</code> argument inside the <code>aes()</code> functions
@@ -8021,7 +8021,7 @@ <h3 class="callout-title">Challenge 5<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solution to Challenge 5</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Here a possible solution: <code>xlab()</code> and <code>ylab()</code>
 set labels for the x and y axes, respectively The axis title, text and
@@ -8184,7 +8184,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Let’s try this on the <code>pop</code> column of the
 <code>gapminder</code> dataset.</p>
@@ -8234,7 +8234,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Refresh your plotting skills by plotting population in millions
 against year.</p>
@@ -8414,7 +8414,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Given the following matrix:</p>
 <div class="codewrapper sourceCode" id="cb28">
@@ -8497,7 +8497,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We’re interested in looking at the sum of the following sequence of
 fractions:</p>
@@ -8821,7 +8821,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>Write a function called <code>kelvin_to_celsius</code> that takes a
 temperature in Kelvin and returns that temperature in Celsius</p>
@@ -8878,7 +8878,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Define the function to convert directly from Fahrenheit to Celsius,
 by reusing these two functions above</p>
@@ -9012,7 +9012,7 @@ <h3 class="callout-title">Challenge 3<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to challenge 3</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Extend our previous definition of the function by adding in an
 explicit call to <code>stopifnot()</code>. Since
@@ -9271,7 +9271,7 @@ <h3 class="callout-title">Challenge 4<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Solution to challenge 4</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9328,7 +9328,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Solution to challenge 5</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>Write a function called <code>fence()</code> that takes two vectors
 as arguments, called <code>text</code> and <code>wrapper</code>, and
@@ -9897,7 +9897,7 @@ <h3 class="callout-title">Challenge 1<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Solution to Challenge 1</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -10127,7 +10127,7 @@ <h3 class="callout-title">Challenge 2<a class="anchor" aria-label="anchor" href=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Solution to Challenge 2</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -10231,7 +10231,7 @@ <h3 class="code-label">R<i aria-hidden="true" data-feather="chevron-left"></i><i
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Solution to Alternative Challenge</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>Answer 3 will calculate the average life expectancy per
 continent.</p>
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