So next week during my normally scheduled ES English club I need help coming up with an activity/game/fun thing. I have 12 regular members ranging from 4-6th graders, mostly 4th graders. I like the club because it's a chance to do games and stuff on a small scale instead of the normal class of about 40 (at this school). However, next week it's a schoolwide club open house/club recruitment for the 3rd graders. This means I'm going to have about 50 3rd graders plus my normal 12 club members.

I need an activity/game/content that works for about 60+ 3-6th graders, is fun and can be done in a classroom. Any suggestions would be appreciated.