Back home, you could probably cuff and slap on the cheek those kids who misbehave in order to teach them a lesson about respecting adults, and their parents would totally support you and punish them for disrespecting another adult. I suggest doing the same here, especially if your Chinese is good enough to explain to them that they are being little racist scums. Although I suspect that the parents would totally freak out and make a scene about the laowai because they consider that treating you like a freak is normal and you asking for normal treatment means you disrespect China or something like that. Pretty retarded society. As for adults, Chinese usually treat Foreigners like freak shows no matter what you do, trying to talk to them about it is a waste of time, the only thing they understand is your fist in their face, but then they hate you even more after that, not that I personally care if they like me.