I understand not wanting to confront the school. Changing an adults behavior is often more difficult than changing a childs. It might even backfire and cause even worse behavior by the teacher in question.
In cases where you cannot change the behavior or remove the child, then I recommend explaining it to the child. I started doing this when my daughter was 2. By the time she was 4, she was able to recognize certain bad behaviors in both adults and children. By understanding this, she is better able to realize it is not personal or because of something she has done.
