Is there a word that refers to an official interest group held in school where registration is totally optional but members once registered are expected to come? Official means the school keeps records and members who do not reach a certain attendance threshold would be kicked out.
I was thinking of school club but that seems to suggest that attendance is totally optional since clubs have the notion of come-and-go-whenever-you-like. On the other hand, the word association or organization sound too business-like.
Besides school club, is there a better word that has a closer meaning to official school interest group?