'Share' Practicing Throwing the Clock

In the university, there was a classroom with a wall clock that had a problem: every time it was hit, it would run faster, gaining 5 minutes per hit. One day, during class, the professor noticed that the students were throwing erasers at the clock while he was writing on the blackboard, but he didn't make a fuss and continued to start and end class according to the clock. Soon, the final exams arrived, and everyone was busy taking the test, only to see the professor practicing throwing the clock with the blackboard eraser.