Flowering plants that live underwater in marine and estuarine habitats (seagrasses) are important because they support human food sources, such as crabs and fish, as well as endangered animals, such as turtles and manatees. Seagrasses are now known to be declining globally, largely as a result of increasing pressure from human populations living along the coast and specifically increasing nutrient inputs. Using a 5e format (Engage, Explore, Explain, Extend, Evaluate) and interactive Web-based delivery for resources, the authors generated materials to cover the who, where, what, and why of seagrass. By learning about seagrasses, including their decline and current seagrass restoration efforts, students will become familiar with ecosystem interactions, global trends, current scientific research, and the decisions and policy-making processes involved in seagrass preservation and conservation. This lesson not only helps students learn about some of the environmental problems caused by the growing human population, but also urges them to become part of a solution. (Contains 3 figures and 2 tables.)