If we already know how to tie our shoelaces, it should not be necessary to learn again. When somebody shows you how to tie them, if you already know how, you may not regard the person as a source of knowledge. Do preschoolers understand the role of learner’s knowledge states in learning the same way? The current study, with seventy-two 3- to 5-year-olds, tested preschoolers’ understanding of learning. Children listened to three teaching stories that a peer tries to teach a knowledgeable, neutral, or ignorant child something, and three not-teaching stories that a knowledgeable, neutral or ignorant child accidently sees the peer do that same thing. We asked if the child would try to learn from the peer, and whether s/he really learned the knowledge from the peer. Results showed an age change in understanding of learning intention and source of knowledge. Relevance to children’s theory of mind is discussed.