As long as you are not ready to change school for your daughter, you, especially your daughter, needs to learn how to deal with teacher who maybe not correct. What you are doing is not wrong , but it is not politically right.
If you started by talking with your daughter
1. Apprise her thinking, and explain to her why her teacher views things differently
2. Then ask her how many choices she has now and what consequences would be if she takes different actions to handle it.
Let her decide what to do. If she wrote an email to the teacher such as: After studies this question more, I still believe..... Would you please explain to me why your answer is only correct one?
Let your daughter understand that opening discussion channel when there is conflict is more important.
Life is not fair and we cannot change other easily. But we have to learn how to coexist with other.
Your daughter is 7th grade now. Maybe it is best to let her in the front line when dealing with her teacher with you be her adviser at background.