We investigated two methods to promote prospective teachers' awareness of learner diversity and application of teaching principles using a problem-based learning environment. In Experiment 1, we examined the effects of presenting a conceptual framework about learners' individual and group differences either before or after instruction on teaching principles. In Experiment 2, we examined the effects of signaling issues of diversity within a set of worked-out classroom cases that were presented in either text or animated format. Learning was measured with a problem-solving transfer test and learning perceptions were measured with program-rating questionnaires. The findings showed a learning advantage for early instruction on individual and group differences in the classroom and participants who learned teaching principles with diversity instruction gave more favorable program ratings than those who did not. Case format did not affect students' learning or perceptions about learning but signaling diversity issues within worked-out classroom cases promoted students' transfer of teaching principles to diverse virtual classrooms and reduced perceived cognitive load. (Contains 2 tables.)