This article in NSTA’s December 2014 issue of “The Science Teacher” describes a classroom activity that uses engineering design to help students model modern fishing gear to minimize bycatch in the tuna fishery. (Bycatch is non-targeted marine species typically caught in fishing gear). The lesson uses the 5E instructional model (Engage, Explore, Explain, Elaborate, Evaluate) and outlines a number of techniques to deepen student understanding of the concepts the model represents. The classroom model employs common household items (e.g., different types of beans, marbles, tennis balls, and buckets) to create a model of the ocean. Working in teams, students modify their “fishing gear” prototype at least three times to target more of the species they want to catch and to minimize catching non-target species. As students optimize their design solutions, they calculate the percentages of target and nontarget species caught in each of the phases of their design process. The teams share their final prototypes and data and then discuss how the engineering process helped them to improve their design over time. Students extend their thinking by considering how their prototypes could be created in real life and then how minimizing bycatch could be accomplished in other ways. Extension ideas are offered to encourage students to explore beyond the lesson in class. Links are provided to additional resources for both learning and assessment. Of particular note is this link: http://www.nsta.org/highschool/connections.aspx which supplements the lesson with both a design rubric and an evaluate rubric, as well as a graphic organizer and an example of a completed graphic organizer.