Evolution is a difficult theory for students to understand. Part of the reason for this may be the tendency of instructors to teach evolution in the context of ecological systems, isolated from genetic and cellular mechanisms. To address this, we developed a set of integrative cases that consider the evolution of traits from the genetic scale to the macroecological scale. We implemented two of these cases in a biology course and tested their effectiveness using a pre-and postcourse assessment tool. Students who successfully learned evolution in a case context were better able to explain the molecular basis of mutation, to connect mutation to phenotypic change, and to make mechanistic links between genotypes and phenotypes. These gains were independent of the students' course achievement and precourse understanding of evolution. These findings support the hypothesis that students who acquire a molecular understanding of evolutionary mechanisms will have a better overall understanding of evolution.