Maybe you misjudged your ability.
Teacher stated she failed me for being a heartless asshole, in writing on my paper.
I also had an Algebra teacher flunk me even though I had a 4.0 score in his class on all his tests because he didn't like the fact that I didn't sit through his boring lectures. Different school, different time period. You shouldn't be graded based on how long you sit for class but how well you know the topic. I was working 100 hours, sometimes 120 hours in a week at the time trying to pay for college as well as rent. I didn't know about Student Loans at that time.