In a recent attempt for a teacher at Georgetown to get students to sign up for his classes, he introduces a new class, Sociology of Hip-Hop: Jay-Z. His normal classes usually ranged from about 20-30 people. After introducing this class, his class size grew seven times what it had previously been. In economic terms, Jay-Z is an incentive. Because Jay-Z is subject of class and more people sign up, there is more of an incentive to sign up for the class.