The Harry Potter series furnishes many instances of both good and bad teaching. From them, we can learn more about three principles outlined in "How People Learn" (National Research Council 2000a). (1) Teachers should question students about their prior knowledge, as Professor Lupin does before his lessons; (2) we should encourage students to develop theoretical contexts in which to organize facts, perhaps through Socratic dialogue such as Professor Dumbledore uses with Harry; and (3) we should promote metacognition, as Harry, Ron and Hermione use when they discuss their successes and failures.