Hi,
No personal experience but an anecdote from a friend. Her DS in K could be interpreted as a bully, laughed at another student (I think called him a baby on multiple occasions in that whisper way so that only the victim hears).
Teacher mentioned it to the bully's mom more as part of a list of being exasperated with the boy. The mom's solution, invite the other child to playdates one on one outside of school. Her son (the bully) is not a bad kid (but definitely does have a flippant jerky side), he was exploring feeling powerful and was not seeing the consequences. Because he didn't really know the child and because he was 6 the bully was able to pretend it was just funny. Having the kids meet elsewhere where there was no one else to impress and no one else more fun to hang out with, and the two parents there hovering and helping the sociability with a fun activity, that did wonders. The bully didn't actually hate the other kid, more had just picked him as easy to tease. While not friends exactly now the two get along fine and no more friction at school. And the parents get along well because they worked together to improve things.
Perhaps the teacher can identify one or more basically nice kids in that group of difficult kids and help with contacting the parents and see about a carefully engineered playdate or activity with one of them at a time. (3 or more is a crowd). Parents working together can make a difference at the age of 5 or 6. These parents may have no idea there's friction and might well be receptive to the idea of a get-to-know-eachother activity.
Polly
