The author examined the degree to which experienced teachers are aware of the relationship between prior knowledge and new learning. Interviews with teachers revealed that they were explicitly aware of when students made connections between prior knowledge and new learning, when they applied their prior knowledge to new contexts, and when they developed their prior knowledge as a result of applying that knowledge to new contexts. However, teachers were not explicitly aware of backward-transfer effects. Results from this study have implications for future research on backward transfer, as well as for teacher professional development.