This lesson plan by New Visions for Public Schools is part of a larger unit called “Ecosystems and Invasive Species” within a one year course called The Living Environment. Each lesson is part of a unit storyline that helps students engage in three-dimensional learning as they make sense of the anchor phenomenon - the zebra mussel invasion into the Hudson River ecosystem. Each lesson may be used alone using a different investigative phenomenon. In each part of this lesson, students use authentic data from the Hudson River to explore different types of organisms interactions (such as predation, competition, symbiosis) that affect populations over time. The lesson follows the 5E model (Engage, Explore, Explain, Elaborate, and Evaluate) and is expected to take 5-8 days of a 45-60 minute class. Teachers can select options, such as how groups are formed or the order of the instructional sequence, within each part of the lesson to achieve instructional goals. Extensive instructional support, student handouts, and a final performance assessment task are provided.