Idea One: I had to do a whole school event once and I got a hold of some stats about Japan, America, and England. I asked the kids questions like: "In which country is a loaf of bread more expensive?" "Which country is the smallest?", "Which country has the most people?" and so on. We did this in a gym and I had the children move to one of three points depending on which they thought was correct.
I told them the answer and the children who answered correctly advanced to the next level. You can also have a bonus question from time to time for the losers, to give them a chacne to get back in the game and also to hold their interest.
This is not an ESL activity, but a good international understanding lesson. I think it will be very hard to teach 200-400 students anything in 30 minutes.
Idea Two: I've always wanted to do this, but never had the crowd. If you're up for a little prep and a challenge. I have some cards I made for comparative practice. They are three teams and it's played like a childrens trading card game. Only, with 200-400 students the students could each be a card (cards player) and they would actually trade/play themselves moving from team to team battling each other. I'll save you some reading time. Please look at the cards and see if you're interested. The page also has an indepth explanation of the game.
www.mes-english.com/games/eigomon.html If you think you might do it, e-mail me and I'd be happy to run through it more thoroughly.
- Mark Cox
www.mes-english.com