How to help students do better in school? Maybe we should try hiring better-looking teachers. Or subsidize gym memberships and makeovers for the teachers we already have.

Those, at least, are the implications of a new study from researchers at the University of Nevada, who designed a simple but revealing experiment using college students to see whether a lecturer’s attractiveness has any impact on how much of the lecture students retain. If you guessed that the answer is yes, go to the head of the class. Extra credit if you...