You need to teach your sons/daughters to tell you about any creepy situation happening. Educate them about not getting money, candy and anything from a stranger especially older than them. If there's a communication between the parents and the childrens then you'd know about if a teacher is getting close to them very soon before something bad happens.
After all, you americans doesn't have anything to do about it. Even if you dislike the fact that a Homo gym teacher is getting to locker rooms, you'd not change it and school administration will not listen to you. You left alot of thing slip from your hands. Personally, I would refuse a homo teacher because I don't want my son to be influenced by behaviours of a homo.