That is the name of a class I taught to a small group of faculty last month. Joe Average is a statistic, not a person, yet many instructors design their courses to teach him. Classes consist of a wide variety of students. They vary in ability and learning style, age and race, gender and religion. If we only appeal to Joe Average, then we appeal to no one. We have visual learners, non-native speakers, young prodigies and military veterans. Does your course engage their interests?
Try designing your courses for the exteme students...the outliers at the edges of the bell curve. If you do, then the rest of the class will take care of itself.