Once every two or three years, a whole high school comes together to put on a big festival! Each classroom, usually six in each year, does something in their homeroom; the class below, 2-6 (second year, sixth class) did some science projects, including a Rube Goldberg machine (which I sadly missed the presentation of.)
Other classes had cafes, gambling casinos (fake 😉 ) or even scaled models of burial mounds, Nagoya castle and the tsunami destruction.
Since the festival is on a weekend, this means that other students can visit and watch their friends (and it does mean the teachers have to work for the weekend as well, but they usually get compensated with a day or two off).
If you’re living in Japan, and have a chance to go to a school festival, take it! Also, take some smaller bills since the students will be selling everything from crepes to corn dogs to ice cream. (or maybe other things as well if they have a bazaar).
By the way, this was in Maebashi at the Boys High School. If anyone reading this lives / wants to visit Gunma, I know that Kiryu Girls High School is having their festival on the weekend of the June 11th and my visit school, Isesaki Shogyou should be having their festival in October.