see you need to do this the proper way, ask your school for that shnazy rule booklet thing and something in there should say like, no skateing, bikeing, etc... on school grounds, BUT! i can almost garantee it says absolutely nothing... so u bring a copy of that shnazy rule book the cop stops u, you tell him to look through that and see if skiing is on that very wounderful list of things your not alowed to do, and when he finds that it isn't then... he can't say shit