"A ceramics professor comes in on the first day of class and divides the students into two sections. He tells one half of the class that their final grade will be based exclusively on the volume of their production; the more they make, the better their grade. The professor tells the other half of the class that they will be graded more traditionally, based solely on the quality of their best piece. At the end of the semester, the professor discovered that the students who were focused on making as many pots as possible also ended up creating the best pots, much better than the pots made by the students who spent all semester trying to create that one perfect pot."