Ahh... the memories.

If your school is composed of one or a few large structures, I've got one for you....

From any (and preferably, most) of the HVAC ducts, dump in roughly one metric shitload (apx 15K total ) of live crickets.

Total investment is minimal. The noise, however, is titanic.. no one, I mean ABSOLUTELY NO ONE will be able to concentrate on anything.

Very fun.