Undergraduate biology majors are often overwhelmed by and underinformed about the diversity and complexity of biological research that is conducted on research-intensive campuses. We present a program that introduces undergraduates to the diversity and scope of biological research and also provides unique teaching opportunities for graduate students and postdoctoral fellows. Explorations are research-based, hands-on classes that are developed and taught by graduate students and postdocs on a specific topic in biology that is not taught in the traditional introductory biology curriculum. These 4-hour, one-time classes are small, interactive, and focused on research experiments. Students have had an overwhelmingly positive response to these explorations; over 92% of students thought that the exploration that they participated in was either excellent or good, and over 96% of students were interested in participating in another one. Furthermore, this program provides graduate students and postdoctoral fellows with a low-time commitment teaching experience that is useful for their professional development. We urge others at research-intensive institutions to consider developing a similar program using graduate students and postdocs as instructors to enrich the experience of undergraduate biology majors. (Contains 4 tables and 4 figures.)