We describe a multiweek laboratory exercise that engages students in class-based research related to sexual reproduction, selection, orientation, and operational sex ratios. Specifically, students discuss contemporary research on sex in the bean beetle, Callosobruchus maculatus, and then develop and test hypotheses related to bean beetle sex. Working with bean beetles is inexpensive and logistically manageable, allowing instructors to scale up to large-enrollment courses. In addition, live organisms engage students in meaningful dialogue related to evolution, sex, and the process of science itself.