Assess students' ability to apply ecological concepts to predict and explain the effects of adding or removing a species from a simple food web. Scope: grade 6–8. Students will identify trophic roles (producers, consumers, predators), analyze direct and indirect interactions (predation, competition), predict population changes and possible trophic cascades, evaluate the role of keystone species, and consider impacts on ecosystem stability and energy flow. Tasks include interpreting provided diagrams or short scenarios, making evidence-based predictions, and justifying answers with clear ecological reasoning.