I am sorry to hear that you have such a problem. First of all, I'm not sure whether the teacher really judges a book by its cover or is biased against you, because I can't understand the specific situation and background. Educational institutions and teachers should treat all students fairly, and should not judge students' performance and value according to appearance or other factors.

If you feel that you have been treated unfairly, I suggest you take the following measures:

Communicate with the teacher: Try to talk to the teacher privately, express your feelings and confusion frankly, and ask if there is anything that needs to be improved or improved. Sometimes it may be caused by misunderstanding or poor communication.

Ask for help: If talking with the teacher can't solve the problem, you can ask the school counselor, class teacher or principal for help and advice.

Seek support: share your experience with family or friends and listen to their advice and support. They may be able to provide you with more support and help.

The most important thing is to keep a positive attitude and pay attention to study and personal growth. Remember, everyone has their own unique values and talents. Don't weaken your confidence because of other people's judgment.