Research shows that teachers presented with new curricula designed to be more student-centered do not usually implement that curricula as intended, even when they receive associated professional development. To date, researchers have examined the implementation issue by focusing on teachers' beliefs, knowledge, and motivations to explain their practices, although results are complex and sometimes contradictory. Similarly, this case study research investigates how a geology instructor (Eric, a pseudonym) chose to implement a student-centered, inquiry-rich, discussion-focused curriculum by using traditional teacher-centered strategies instead. Classroom observations and multiple audio-recorded meetings with Eric were a means to understand why he chose and amended certain parts of the proposed curriculum. The object of focus is Eric's spontaneous use of metaphor when talking about teaching, learning, and knowledge to understand and explain the factors involved in his instructional decision making. Analyzing Eric's conversations and teaching through an embodied cognition theoretical framework shows that he structured his teaching with two metaphors: the jigsaw puzzle metaphor and the fieldtrip metaphor. These parallel metaphors worked in concert to shape how Eric perceived his role, his students' role, and the role and nature of knowledge; thus, they structured what and how he taught. Understanding teachers' conceptual metaphors can aid curriculum designers to develop content with a higher likelihood of implementation, just as collaboration and communication between designers and teachers will support teaching-in-the-making.