Ansatsu Kyoushitsu: Kagaijugyou-hen
English name: Assassination Classroom: Extracurricular Lesson
Genres: Action, Comedy
Type: ONA, Episodes: 8
Aired: Mar 11, 2016 to May 20, 2016
Studio: Lerche
Source: Manga
Rating: PG-13 - Teens 13 or older
Synopsis:
Shorts of Ansatsu Kyoushitsu 2nd Season which adapt chapters of the manga which are not in the TV series. 

The adapted chapters are 78 ("Takebayashi no Jikan") and 79 ("Shihaisha no Jikan, Ni Jikanme"), which are published in the ninth manga volume.