Ecological succession explored at the secondary and postsecondary level is often limited to terrestrial ecosystems. The emphasis is traditionally placed on how deforestation leads to ecological succession. However, aquatic ecological succession is just as important and allows for many connections to be made with other ecological concepts. Succession initiated by beavers (Castor canadensis) in particular links both aquatic and terrestrial ecosystems over time. We present a guide to an inquiry-based lesson for AP Environmental Science and undergraduate ecology courses that explores the effects of aquatic and terrestrial ecological succession initiated by deforestation and beavers. Specifically, the focus is ecological succession and its effects in both terrestrial and aquatic ecosystems. In this lesson, students (1) engage with a preassessment and broad overview of ecological succession, (2) explore authentic research data representing secondary succession in beaver ponds, (3) explain data using detective activities, (4) elaborate with a mystery pond, and (5) evaluate their new understanding by comparing a pre- and postassessment. This lesson plan meets the objectives for AP Environmental Science Biology courses as well as the core concepts and competencies for undergraduate biology education from the Vision and Change report by the American Association for the Advancement of Science in 2011.