Assess graduate students' understanding of conceptual models describing nutrient (primarily N and P) cycling and drivers of eutrophication in temperate freshwater lakes, including external vs. internal loading, sediment–water exchanges, biogeochemical transformations, seasonal stratification and turnover, food‑web interactions, common modeling approaches (box/mass-balance models), interpretation of model diagrams and fluxes, and implications for monitoring and management (load reduction, internal control, indicators of trophic state).