diff --git a/app/models/test_pair.rb b/app/models/test_pair.rb
--- a/app/models/test_pair.rb
+++ b/app/models/test_pair.rb
@@ -1,3 +1,9 @@
+# TestPair stores an input-solution pair for a problem.  This is used
+# in a certain "test-pair"-type problem for the CodeJom competition
+# which follows the Google Code Jam format, i.e., a participant only
+# submits a solution to a single random input that the participant
+# requested.  This input-solution pair is a TestPair.
+
 class TestPair < ActiveRecord::Base
-  belongs_to :problem
+  belongs_to :problem    
 end