Bunkasai (文化祭), the “Japanese Cultural festival”, is an important event at nearly every school in Japan from junior high to university (the dates ares different from school to school, to allow observers to attend multiple events). It’s a day to show off the students’ talents and the school itself to parents and prospective students. Instead of a shrine-based matsuri, a? festival episode may be well based at school’s Bunkasai.
Traditionally, most schools hold Bunkasai in autumn. This is around late October and November. Normally it is held on a Saturday or Sunday sometimes even both and open to everyone.
Each homeroom class will put on some sort of event (justified form the educational standpoint as teaching the students how to run a business); the two common involve turning a classroom either into a small cafe (kissaten), or a haunted house (obakeyashiki). This itself has become such an ingrained part of the trope that it is rare to see any other possibilities? discussed? when a class is trying to decide what to do for their participation in the festival but carnival games and student-crafts shops crop up from time to time.
Student clubs will also participate, generally creating club-theme-related attractions in hopes to attract future recruits. Theme costumes will be commonplace.
In addition to events held within the school proper, with classrooms temporarily transformed into shops, the schools grounds will be used for outdoor stalls like those of a shrine matsuri.
It’s highly likely that any manga or anime set primarily in a school will have a Bunkasai episode.
Here find some links to pictures of Bunkasai :