I agree with Carrie, ignore the dog and get the teacher to do something about it. 4 weeks is a long time, the teacher is the one who should be disciplining the dog and providing a safe environment for her students. She'll be lucky if that dog never bites anyone and she's never sued. And to think she subjects kids to that is scary.

I'd be afraid to stick my hand out to give the dog a treat - and I'm sure the dog would know and take advantage of that fear!