Slander/Prejudice law suit?

My son worked his off on a college paper, the first written paper of the semester for this cl. When he handed the paper in to the teacher, the teacher called him out for plagiarism. She said that he was incapable of writing the paper because he was an athlete and knows how athletes are in school. So basically she completely steriotyped my son and was prejudice towords him. Now she is not being cooperative and being very rude to me and my wife who have tried to explain the truth of the situation to her, so we are ready to take it to the next level maybe a law suit? would we have a case?