In the study discussed in this paper, we investigated the question: How do prospective teachers use content knowledge when analyzing video tapes of elementary children learning physics? We found that prospective teachers used content knowledge in three different ways: (1) restating children’s ideas, (2) reflecting on their own learning, and (3) discussing the content involved in the elementary student videos directly. In this paper, we present detailed examples of events included in the restating children’s ideas category which illustrate prospective teachers’ use of pedagogically-relevant content knowledge, a type of knowledge used by teachers which is often referred to as pedagogical content knowledge or PCK [7] in the teacher education literature