ZX Spectrum game. You would walk around school and cause as much mischief as possible without being caught by a teacher. You could use your catapult to shoot at teachers. You did however have to go to class, which involved trying to find the room then invariably pushing someone out of their seat before the teacher turned round to see you.

My memories of this game are fairly hazy, but I suppose someone has an emulator for it now to save me hunting out the tape :)