Only let students pay the percent of tuition they don't pass

My petition is going out to all of the colleges. Colleges should only let students pay the amount of tuition they don't pass. An example would be, You are in an English class at some college. At the end of the semester, you have a 83% in that class now for your tuition would would only have to pay 17% of the money in for the class. Not only would you let the students pay for somewhat of the tuition but, you would also be rewarding the people who are actually there to pass their classes and go succeed. Some people only go to college to party and don't pass any of their classes. This would be a great strategy to come through our government system and help people who can't afford the whole semester.