Okay...my stepson is 5 and they put him in pre K because of his birthday,?

but he has been in school since he was a year old. He has been getting in trouble for talking out of term and for playing around while the teacher is speaking and teaching. Now....he never does this at home or at his mothers and he usually listens the first time right away. I know this sounds strange but it is true he does. I think that the problem is that he is bored becuase he already knows his abc's 123's and he already knows how to add, subtract and Multiply. The teacher says it is because we pay too much attention to him and that he is too used to being the center of attention and that we should puprosely go and get an ice cream without getting him one so that he feels bad when he doesn't listen the first time. I think that this is cruel. Any advice. I would never rub something in my childs face....and she made my stepsons mother, my husband and myself feel that we were terrible parents. He has always been very well behaved at school and this is a first. Any suggestions?