I've had my ileostomy since I was 10 years old so know what it's like to go through school with one.
The only people who ever knew about my bag were my teachers and my closest friends. The rest of the kids knew I'd had abdominal surgery but didn't really know the details of it - and that's the way I liked it.
My ostomy did get me out of sports (no reason it should really except I hated sports and the teachers didn't know any better and I wasn't about to tell them :) ). What good is having major surgery if you can't play on it once in a while :)
My surgery was due to UC and I've had my ileo for 30 years so far and it has never really been a problem for me. Sure, there are a few teething problems in the beginning, just like with anything in life but once you get those teething problems fixed, life can be 'normal' just like those with bowels intact. I've traveled the world, ridden elephants and camels, been rock climbing, swim regularly every summer, etc all without a problem.
Good luck and let us know how you're going.
I have had an ileostomy for 30 years now due to UC.
I'm not a complete idiot - some parts of me are missing!