Even if you've been long removed from the day-to-day realities of class schedules, college ruled notebooks and the quadratic formula, you still might have midnight hauntings of pop-quizzes and impossible exams. Subconscious test anxiety is actually quite common among dreamers, and the grade you receive on your exam is fascinatingly revealing.
Failing an exam in your dreams reflects your waking life concerns about how deserving you are for the things you have achieved in life. If you were to go back and receive an evaluation of all your past deeds, would you be satisfied with the results? If you would be satisfied, but you feel the grade you received on your dream-exam was unfounded or incorrect, your dream might be suggesting your feelings of doubted or denied recognition for something you've accomplished.