What do you do about behavior issues away from you?

Thanks everyone for the advice. I feel a little better to hear that others think the teacher isn't holding up her end of the bargain. But I am still ultimately responsible for my child's behavior, and technically he shouldn't even be behaving that way in the first place. So even if the teacher isn't doing anything I still have to figure out a way to get through to him. We did have a long talk with him Friday morning and discussed "earning" something with stickers. We decided that once he'd earned 20 stickers that I would take him shopping for a new pair of pajamas -- with feet. I talked to his teacher Friday afternoon and his behavior had improved hugely, and he'd earned 7 stickers already. So we will see how things go. I am hoping that if he gets to figure out beforehand what he wants his reward to be that he will be more inclined to work for it. I haven't heard how today went so hopefully they didn't go back to square one today. Now, this is going to hinge on the teacher giving him opportunities to earn stickers ... so this may end up fizzling out if she stops giving him opportunities. I guess we will see how it goes.