Engaging students in the process of science to increase learning and critical thinking has become a key emphasis in undergraduate education. Introducing environmental topics, such as the effects of endocrinedisrupting chemicals, into undergraduate courses offers a new means to increase student engagement. Daphnia magna can serve as a model organism for endocrine disruption, and its ease of handling, rapid reproduction rate, and clearly defined endpoints make it useful in short-term, student research projects. The concept of endocrine disruption can be tested through a 21-day reproductive study of D. magna exposed to varying concentrations of the pesticide fenoxycarb. Students will observe an altered reproduction rate and increased production of males under conditions that would typically result only in the production of female offspring. This research system allows students to formulate hypotheses, set up experiments, analyze data, and present results, leading to a greater appreciation of and interest in science.