My experience has been that kids will either live up to clearly expressed expectations or they will go elsewhere. If there are sufficient attractions for a child in a place with high expectations, he or she will try hard to live up to the standards. I also find they will modify their behavior when I make it plain I will be watching. Some of them, the middle schoolers in particular, are manifestly not used to adults paying any attention to what they do, so they are somewhat taken aback by this.

I have never been shy about enforcing standards of behavior for other people's children on my turf, be it in my neighborhood or at work. Frankly, even though I understand this is out of fashion, I don't care, and I don't know why anyone should hesitate to correct a kid who's out of line. People say please and thank you and treat each other with common courtesy in the Youth Library, or they find themselves not there anymore. I don't require quiet, but manners are enforced.

Children will live up to the standards set for them. If children act rude, it means the standards have been set too low, and it's not up to them to change that. It's up to the adults. After standards have been raised, then it's the children's job to behave accordingly.