If he can't bring cards then oh well, that shouldn't limit you at all. If kids are grabbing cards and coins or whatever out of your hands then you need to learn some croud control and gain some respect as a magician. Also "I know how you did it kids" are called heckers, most of the time they're hecklers. If you can't control your crowd and people grab your stuff don't do tricks for them. If you can then i like to make fools of them
. Head Trip from on the spot usually does it, if not i get a little more into it. Getting your teachers to do tricks for them is great, it shows that they really enjoy it and don't think you're lame.
EDIT: Punctured, Stealth Pen, PK rings, and coin magic is your best bet at school, I am also not allowed to bring cards, so I use coins and pens. PK rings are great, I just ordered the Blacks PK ring and can't wait. Hummer cards and other IT tricks aren't a good idea because kids like to grab things and IT is the last thing you want people to know you are using.