An extensive body of work has documented the impact of analogous cases on transfer. However, far less work has explored the role of contrasting cases in facilitating transfer. We designed a novel contrasting cases activity to engage learners with center-of-mass concepts in an engineering design task – building a cantilever using Legos. Participants in three conditions analyzed either contrasting cases, single cases, or no cases in the midst of an engineering design activity. Contrasting cases facilitated near but not far transfer. However, all conditions built equally successful cantilevers and noticed the underlying structure of center-of-mass concepts to the same degree. Moreover, regardless of condition, participants who noticed the structure at a deeper level performed better on both the engineering task and the far transfer assessment. The work has implications for the design of science and engineering instruction, while expanding our understanding of the perceptual processes that underlie transfer.