Evolution by natural selection and adaptation are core concepts in biology that students must see and correctly understand their meaning. However, using these concepts in evidence-based learning strategies in the classroom is a difficult task. Here, we present a 5E lesson plan to address the Next Generation Science Standards performance expectation HS-LS4-4, to “construct an explanation based on evidence for how natural selection leads to adaptation of populations.” The Functional Frogs lesson provides multiple hands-on activities to engage students in the development of hypotheses, collection and analysis of empirical data on frog swimming, presentation of results, and construction of explanations supported by evidence for the results. The lesson's central idea is for students to understand the trait values that provide an advantage in the aquatic environment, increasing a frog's survival. The link between morphological changes and survival is used to explain how natural selection acts on populations, leading to adaptive evolution.