Teaching and preschoolers' ability to infer knowledge from mistakes

For instruction to be effective, teachers must adjust the way they teach to match what learners know. We asked whether children's ability to infer what someone knows based on his or her mistakes develops alongside their teaching-children's use of more explicit teaching strategies and their ability to tailor how much information to provide in response to their pupils' mistakes. Preschoolers (N=48) were taught a simple game and were then introduced to four puppets: one puppet who played the game perfectly, two puppets who each made one mistake, and one puppet who made two mistakes. After watching each puppet play individually, children were asked to rate the puppet's understanding of the game and then were invited to teach the puppet. Children's ability to monitor the relative accuracy of the puppets-the ability to make nuanced judgments about what each puppet understood based on each puppet's unique mistakes-improved with age. Moreover, older children were more explicit and more precise teachers than younger children. They more often contrasted the learners' mistakes with what should be done and more often provided instructions that directly addressed the puppets' unique mistakes. Thus, between 3 and 5 years of age, developments in children's ability to infer knowledge from mistakes parallel developments both in the strategies children use to teach and in the amount of information they teach in response to mistakes.