Assess students' understanding of the global carbon cycle for grades 9–12: identify major reservoirs (atmosphere, biosphere, hydrosphere, lithosphere), describe key fluxes and processes (photosynthesis, respiration, decomposition, ocean uptake/release, sedimentation, volcanic outgassing, combustion), compare timescales, and explain how human activities (fossil fuel burning, deforestation, cement production, land-use change) alter atmospheric CO2, sink strengths, and climate-relevant feedbacks; tasks may include diagram labeling, short explanations of pathways, interpreting CO2 trend data, and qualitative/quantitative reasoning about source–sink changes.