diff --git a/app/models/challenge.rb b/app/models/challenge.rb
index 6567dfa6..aaea5d27 100644
--- a/app/models/challenge.rb
+++ b/app/models/challenge.rb
@@ -12,6 +12,7 @@ class Challenge < ApplicationRecord
 
   before_create { |challenge| challenge.flag = BCrypt::Password.create(flag) }
 
+  default_scope { order(title: :asc) }
   scope :active, -> { where(active: true) }
 
   class String < SimpleDelegator
diff --git a/app/models/submission.rb b/app/models/submission.rb
index a41047b3..58af6d1b 100644
--- a/app/models/submission.rb
+++ b/app/models/submission.rb
@@ -8,4 +8,6 @@ class Submission < ApplicationRecord
 
   validates :submission_hash, presence: true, uniqueness: true
   validates :user, :team, :challenge, :category, presence: true
+
+  scope :valid, -> { where(valid_submission: true) }
 end
diff --git a/app/models/team.rb b/app/models/team.rb
index 54906dd7..5de0ed35 100644
--- a/app/models/team.rb
+++ b/app/models/team.rb
@@ -9,4 +9,8 @@ class Team < ApplicationRecord
             uniqueness: { case_sensitive: false }
 
   include Tokenable
+
+  def solved_challenges
+    submissions.valid
+  end
 end
diff --git a/spec/factories.rb b/spec/factories.rb
index ae13e2f5..829723ee 100644
--- a/spec/factories.rb
+++ b/spec/factories.rb
@@ -27,7 +27,7 @@
   end
 
   factory :category do
-    name { 'web' }
+    sequence(:name) { |n| "category-#{n}" }
   end
 
   factory :challenge do
@@ -53,7 +53,7 @@
 
   factory :submission do
     challenge
-    category
+    category { challenge.category }
     flag { 'flag{invalid}' }
     user
     team
diff --git a/spec/models/challenge_spec.rb b/spec/models/challenge_spec.rb
index d542761d..cc738761 100644
--- a/spec/models/challenge_spec.rb
+++ b/spec/models/challenge_spec.rb
@@ -63,4 +63,13 @@
       expect(@challenge.description.to_md).to eq("<h1>Finish the challenge to get the flag</h1>\n")
     end
   end
+
+  context 'when calling for challenges' do
+    let(:challenge_second) { FactoryBot.create(:challenge, title: 'challenge2', flag: 'flag{flag}') }
+    let(:challenge_first) { FactoryBot.create(:challenge, title: 'challenge1', flag: 'flag{flag}') }
+
+    it 'returns them sorted by title' do
+      expect(Challenge.all).to eq([challenge_first, challenge_second, @challenge])
+    end
+  end
 end
diff --git a/spec/models/submission_spec.rb b/spec/models/submission_spec.rb
index ab9411f9..2dbda29c 100644
--- a/spec/models/submission_spec.rb
+++ b/spec/models/submission_spec.rb
@@ -111,4 +111,11 @@
       ).to_not be_valid
     end
   end
+
+  context'when calling #valid' do
+    let(:valid_submission) { FactoryBot.create(:submission, valid_submission: true, flag: nil) }
+    it 'returns valid submissions' do
+      expect(Submission.valid).to eq([valid_submission])
+    end
+  end
 end
diff --git a/spec/models/team_spec.rb b/spec/models/team_spec.rb
index 0f0e83d7..93cdd442 100644
--- a/spec/models/team_spec.rb
+++ b/spec/models/team_spec.rb
@@ -24,6 +24,15 @@
     end
   end
 
+  context 'when calling #solved_challenges' do
+    let(:team) { FactoryBot.create(:team) }
+    let(:submission) { FactoryBot.create(:submission, valid_submission: true, flag: nil, team: team) }
+
+    it 'returns a list of valid submissions' do
+      expect(team.solved_challenges).to eq([submission])
+    end
+  end
+
   private
 
   def create_users