I think it is a lot to expect teenagers (or elementary school aged kids) to serve as missionaries or change agents in public schools. The deck is stacked heavily against them.
It wouldn't hurt for them to ask a schoolmate to church or to join the Boy Scouts but, they need not be in the hallways with a blow horn.
Peer pressure works both ways.
Needless to say, (and I'll repeat as necessary) ignoring the problem will not make it go away, it will only fester.Those *other* children are also our future.