Two university students had a week of exams coming up but decided to party instead. When they got to their exam they decided to tell the professor their car had broken down the night before due to a flat tyre and they needed a bit more time to study.

The professor told them they could have another day to study.

That evening, both of the boys crammed all night until they were sure they knew just about everything. Arriving at class the next morning, each boy was told to go to a separate classroom to take the exam. Each shrugged and went to different parts of the building. As each sat down they read the first question. "For 5 points, explain the contents of an atom." At this point they both thought this was going to be a piece of cake and answered the question with ease. The test continued.... "For 95 points, tell me which tyre it was."