diff --git a/app/models/test_pair_assignment.rb b/app/models/test_pair_assignment.rb
--- a/app/models/test_pair_assignment.rb
+++ b/app/models/test_pair_assignment.rb
@@ -1,5 +1,11 @@
 class TestPairAssignment < ActiveRecord::Base
+
   belongs_to :user
   belongs_to :test_pair
   belongs_to :problem
+
+  def expired?
+    return created_at + TEST_ASSIGNMENT_EXPIRATION_DURATION < Time.new.gmtime 
+  end
+
 end