Laboratories in introductory biology must engage and excite students in ways that effectively prepare them to succeed in upper-level courses in a field with a rapidly increasing body of knowledge. Our inquiry-based lab immerses students in the process of science by asking them to develop behavioral bioassays to test the response of aquatic macroinvertebrates to various pollutants. Students begin with literature review and hypothesis generation on an open-ended question; continue through experimental design, data collection, and analysis; and finish with writing a paper that is peer reviewed. A series of weekly lab activities serves to scaffold key skills that enable completion of the behavioral bioassays, and a final field aquaticbiomonitoring project connects lab work to real-life environmental issues. Because not much is known about how certain pollutants affect the behavior of specific aquatic invertebrates, students' curiosity is piqued by new discovery, and instructors are engaged by the sense of partnering with students to explore the unknown. This module requires that students engage in core biological concepts, including the significance of variation in living organisms, the structure and function of organisms, and impacts of environmental change on both homeostasis and populations.