Baka to Test to Shoukanjuu
Is a Japanese light novel series created by Kenji Inoue and illustrations by Yui Haga.
A 13-episode anime adaptation produced by the animation studio Silver Link and directed by Shin Onuma aired in Japan between January 7 and March 31, 2010.
Then 2 OVAs came out Feb-March 2011, then another 13 TV episodes July-September 2011. This brings the total to 28 anime episodes.