Zoonotic diseases pass between humans and other animals and are a major global health challenge. Lyme disease, SARS, swine flu, and Ebola are all examples of diseases spilling over to humans from other animals. Students may hear about these outbreaks in the news but learn very little about them in the classroom. We describe an activity designed to teach high school or college students about zoonotic disease outbreaks. This case-based lesson also introduces how habitat disruption can lead to far-reaching impacts on livestock and humans, often indirectly. Collaborative problem solving is used to explore the One Health concept and a real-world spillover event involving Hendra virus. Active learning using a “jigsaw” format to model the value of multiple stakeholders engages students in tracing the path of transmission for a pathogen. The scenario and class activity demonstrate how scientists and health professionals routinely work together to figure out the chain of transmission for a novel pathogen and use this information to limit the spread of disease.