A case study is an excellent way to help students think like scientists as they work to solve a dilemma. This article describes a case study of elk in Yellowstone National Park. Students read short narratives, based on scientific research data, about the puzzling question of why some elk live substantially longer than others in certain areas of Yellowstone. Each successive narrative provides more clues to solving this puzzle. Students are encouraged to model scientists' approach by asking questions, examining evidence, and designing possible research studies to find answers to the question of elk mortality. (Contains 1 figure and 6 online resources.)