Dear Ashlee,
Your teacher should not be discussing the kind of student you are with anyone, except, of course, you and your parents. Before you get really angry with the teacher and take action, make sure that your friend has given you accurate information about what your math teacher said. Then, see your teacher before or after class and tell her that you want to do better in class and could use some help. Let her know that if she has a problem with you as a student, you'd really appreciate it if she would talk to you directly instead of to another student. If your teacher continues to act in inappropriate ways, ask your parent or the school principal for help.