It seems we have gotten off the original topic, Is it a good idea for kids to perform at school or not?
It seems that a lot of the posters here are school aged, performing for their friends, (and possibly some enemies as well).
Be careful of who you are performing for, and for what purpose. If it is to entertain, amuse, bemuse, befuddle, or bedazzle, then you are on the right track. If you are performing for respect, I think you may be setting yourself up. What's going to happen when those who "respect" you happen to catch you when you mess up, and are exposed. False respect is not respect, in fact, I'd wager that the moment you flub an effect, they'll turn on you like hungry wolves.
The point is, I have seen kids, very good magicians, shot down by their "friends" the moment they made a mistake. I usually never perform for friends, unless they're paying me, or they're at one of my gigs. I do this because my friends have put me through the wringer when I've made a mistake, mostly because they can!
For school aged performers, I reccomend family, or family friends, and, as has been posted, the best friend who totally supports your art. And, as I've stated, gentlemen, be careful doing effects for the ladies. Show them stuff, yes, just be very careful.........