Unfair Grade: Teacher Doesn't Agree With Student's Political View Education & Careers Jobs
I don't call for people to get fired often, but such a scenario would provoke such a response. The only time politics should enter a classroom is if it is the subject of study, and then it must be presented as neutrally as possible. For it to impact a student in such a way would be a massive offense, easily on par with a teacher taking bribes for good grades
Now, with that stated, Kntoran is correct, in many cases, proving the reason for the grades is related to political differences rather than understanding will often be difficult.