Design a 30-minute active-play routine for Grade 3–5 students that includes a dynamic warm-up, a main aerobic/activity block, strength and flexibility exercises, and a cool-down. For each segment, specify time allocation, 2–3 concrete activities, equipment and setup, safety and age-appropriate modifications, and one measure of student engagement/intensity. Briefly explain the purpose and expected physiological and motor-skill benefits of each part and how it supports classroom behavior and learning. Provide one low-space or limited-equipment variation and note any assessment indicators teachers can use to gauge effectiveness.