Human-made pollution is a large and complex problem that has harmful effects on communities and ecosystems. Understanding these impacts is essential, but it can be daunting when many types of chemical pollution are difficult to conceptualize, especially for elementary school students. Something every student can understand, however, is trash. Students have seen plastic, glass, paper, and metal litter items along roadsides, falling out of trash cans, and in rivers. Since trash is a concrete example of pollution, something that students can easily see and relate to, it is an excellent starting point to learn about pollution of any kind. In this article, the authors present an inquiry unit for fourth- and fifth-grade classrooms designed to build students' understanding of trash pollution, discover its environmental effects, and communicate how people in their community can reduce those effects. It was created as a collaboration between a team of fourth-grade teachers and an ecology research laboratory at a local university. This series of lessons was designed to integrate the use of articles, websites, data charts, and videos into a framework for students to develop scientific research and communication skills, using trash pollution as the anchoring theme. The unit culminates in students using their research to create a public service announcement to report pollution findings and possible solutions that could be shared with other students and the community.