Does your teacher not discipline the dog? I would ask her about the dog's behavior. Does it bite ALL her students?

Hopefully, the dog will adjust, will get used to you being there. It must see you as an intruder, and your teacher should be dealing with that! I, frankly, would try bringing a dog biscuit with me every time, asking your teacher if it's okay, and showing the dog the biscuit when you first get there. If it acts threatening, put the biscuit away, but if it is quiet, give it the biscuit.

Of course, you should talk to your teacher, and ask her to keep the dog in a seperate room when you come for your lesson, but I'd try either making friends with it, (even bribing) or ignoring it.