Embedding science learning in real-world issues is a research-based way to generate student enthusiasm, interest, and motivation for science. The authors advocate teaching secondary science in the context of "socio-scientific issues" (SSI). SSI are authentic societal challenges with connections to science, such as climate change, antibiotic resistance, and fracking. Because they are controversial topics, addressing SSI requires both an understanding of relevant science ideas and thoughtful consideration of an issue's social, economic, political, and ethical aspects. SSI-based units integrate relevant science ideas with social aspects of SSI and include lessons focused explicitly on each. Because of this, teaching science with SSI may require innovative instructional strategies. In this article, the authors share a timeline activity they developed that uses one such strategy to help high school students explore societal aspects of an SSI. The unit is centered around the SSI of a proposed tax on obesogenic foods, or foods that are thought to promote excessive weight gain, and is designed to teach about energy systems through nutrition at the high school level.