I can’t stand Obama, but the teacher was wrong. You don’t do that sort of thing in a school context.
To give her the benefit of the doubt, you don’t know the context or the actual content or the manner of hers statement. To whom she was speaking. Maybe she was responding to some wise-ass kid. To be sure , you can’t expect much sympathy from a bunch of black kids for whom this very bad man is a hero and role model.