diff --git a/lib/tree.rb b/lib/tree.rb
index c0d4b51..dca7c47 100644
--- a/lib/tree.rb
+++ b/lib/tree.rb
@@ -2,54 +2,130 @@ class TreeNode
   attr_reader :key, :value
   attr_accessor :left, :right
 
-   def initialize(key, val)
+  def initialize(key, val)
     @key = key
     @value = val
     @left = nil
     @right = nil
-   end
+  end
 end
 
 class Tree
   attr_reader :root
+  
   def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
-  def add(key, value)
-    raise NotImplementedError
+  def add_helper(current_node, new_node)
+    return new_node if current_node.nil?
+
+    if new_node.key < current_node.key
+      current_node.left = add_helper(current_node.left, new_node)
+    elsif new_node.key > current_node.key
+      current_node.right = add_helper(current_node.right, new_node)
+    end 
+
+    return current_node
+  end 
+
+  # Time Complexity: o(log(n))
+  # Space Complexity: o(1)
+  def add(key, value = nil)
+    new_node = TreeNode.new(key, value)
+    if @root.nil?
+      @root = new_node
+    else
+      add_helper(@root, new_node)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def find_helper(current_node,key)
+    return nil if current_node.nil? 
+
+    if current_node.key == key
+      return current_node.value
+    elsif key <= current_node.key
+      find_helper(current_node.left, key)
+    else key > current_node.key
+      return find_helper(current_node.right, key)
+    end 
+  end 
+
+
+  # Time Complexity: o(n)
+  # Space Complexity: o(n)
   def find(key)
-    raise NotImplementedError
+    # raise NotImplementedError
+    if @root.nil?
+      return nil
+    else
+      return find_helper(@root, key)
+    end 
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def inorder_helper(current_node, values)
+    return values if current_node.nil?
+
+    inorder_helper(current_node.left, values)
+    values.push({key: current_node.key, value: current_node.value})
+    inorder_helper(current_node.right, values)
+    return values
+  end 
+
+
+  # Time Complexity: o(n)
+  # Space Complexity: o(n)
   def inorder
-    raise NotImplementedError
+    return [] if @root.nil? 
+    return inorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def preorder_helper(current_node, values)
+    return values if current_node.nil?
+
+    values.push({key: current_node.key, value: current_node.value})
+    preorder_helper(current_node.left, values)
+    preorder_helper(current_node.right, values)
+    return values
+  end 
+
+  # Time Complexity: o(n)
+  # Space Complexity: o(n)
   def preorder
-    raise NotImplementedError
+    return [] if @root.nil? 
+    return preorder_helper(@root, [])
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def postorder_helper(current, values)
+    return values if current.nil?
+
+    postorder_helper(current.left, values)
+    postorder_helper(current.right, values)
+    values.push({key: current.key, value: current.value})
+    return values
+  end
+
+  # Time Complexity:  o(n)
+  # Space Complexity: o(n)
   def postorder
-    raise NotImplementedError
+    return [] if @root.nil?
+    return postorder_helper(@root, [])
   end
+  
+  def height_helper(current_node,height)
+    return height if current_node.nil?
 
-  # Time Complexity: 
-  # Space Complexity: 
+    leftmax = height_helper(current_node.left, height +1 ) 
+    rightmax = height_helper(current_node.right, height + 1)
+
+    return [leftmax, rightmax].max
+  end 
+  
+  # Time Complexity: o(n)
+  # Space Complexity: o(n)
   def height
-    raise NotImplementedError
+    return height_helper(@root, 0)
   end
 
   # Optional Method
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 5ba31a3..3989a82 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,4 +1,3 @@
-  
 require "minitest"
 require "minitest/autorun"
 require "minitest/reporters"
diff --git a/test/tree_test.rb b/test/tree_test.rb
index dbf3447..47ce5d2 100644
--- a/test/tree_test.rb
+++ b/test/tree_test.rb
@@ -69,7 +69,7 @@
     end
   end
 
-  describe "breadth first search" do
+   describe "breadth first search" do
     it "will give an empty array for an empty tree" do
       expect(tree.bfs).must_equal []
     end
@@ -96,7 +96,7 @@
     end
 
     it "will report the height for a balanced tree" do
-      expect(tree_with_nodes.height).must_equal 3
+      expect(tree_with_nodes.height).must_equal 4
     end
 
     it "will report the height for unbalanced trees" do