In most areas it's just a school rule which they could punish you for. You should check out your local laws before doing so. I believe they dont see it as illegal and wouldn't punish you in a court of law.     As for concealing it get a backpack with a nice hidden extra pocket and keep it in there away from everything else. A small compact will do nicely. Try the Glock 26 - 9mm. That's what my wife carries. Make sure you have a good holster so that nothing could snag it.    Ultimately it's your life and your decision on what you feel is right for you. I am just telling you what I would do or tell my wife to do in your situation.    Learn your gun inside and out. Practice with it as much as possible.    Good luck