I would try first going to the school counselor, if they have one. It would be a real shame if she got discouraged because of what the man is doing.
I believe that if they tried to fire you, that you are covered by the school's policies, you would have to check with your local school board to be sure. But if as you say he has done this to your son and another co-workers child, I would say there may be others. If it comes to it, you could both go down and report what is going on to the board.
Then the counselor could decreatly talk to the teacher and let him know and talk about it, or better yet, talk to you both.
Your daughter needs to know you will stand up for her, when she is right and not let him get away with it. With her good grades it should be proof enough that shes not a slacker who talks all the time.
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