Unity! Empty Cans! Cultural Festival! (団結! 空き缶! 文化祭! Danketsu! Aki Kan! Bunkasai!) is the 11th episode of Kono Bijutsubu ni wa Mondai ga Aru! series, which was aired on Sep 15, 2016.
The cultural festival is upcoming, and after knowing that last year the Art Club did not anything for it, Tachibana-sensei decides to collect empty cans to make a tin can art with the Art Club for the cultural festival using only cans from the school and the theme will be "made in school". They begin to look for any idea for the art. At the frist day they don't get to think in anything, but at night Usami thinks in a tube of paint, and next day Imari and Uchimaki help giving the idea of to have some paint spilling out. Then they (the art club members, Tachibana-sensei and Imari) go to take cans in the school and get a lot, but due to a misunderstanding, Moroboshi-sensei throw away many cans, so President has the idea to buy some refrigerant at the supermarket and to sell it at the school, thus the material will continue to be "made in school" and it was a success. After the art is done, they realize that is impossible to carry it to the gym, where it will be displayed, then they decide to tear it down and mount again.
Episode Notes 
Manga & Anime Differences
- The "Challenger" appears again and challenges Uchimaki to drink the refrigerant fastest.
- The song Kokoro Palette is aired.