We have a bit of the flip version of this. DS9 was often spoken too for dominating classroom discussions. The teachers and I had to tell him that we know HE knows - he needs to let the rest of the kids demonstrate that THEY know. But he does love to share things with the teachers that he thinks THEY don't know...LOL Also a discussion that although the teachers know he knows the material he still needs to do his work etc. so that they can give him the grades his knowledge deserves. Luckily this year he has teachers that do their best to challenge him.