Design a comprehensive, evidence-based, culturally sensitive K–12 school-based physical activity and nutrition intervention that integrates behavior-change theories, standards-aligned curriculum and school policy components, family and community engagement strategies, monitoring and assessment protocols (process, fidelity, short- and long-term outcome measures), and a rigorous evaluation plan (study design, sampling and power, primary/secondary outcomes, analysis methods, cost-effectiveness, and ethics). Define program goals and a logic model, specify grade-band activities and implementation supports, detail measurable indicators and data-collection tools, and propose an evaluation timeline, dissemination strategy, and plans for scalability and equity monitoring.