Have you ever wondered why runners start at different spots on a track instead of lining up together? This is called a staggered start. Since tracks have semicircles (or half circles) on the ends, if all the runners lined up together, runners in outer lanes would need to run farther than runners in inner lanes. Why? Because the circumference of the outer lane is greater than the circumference of the inner lane. Staggering starting positions ensures that all runners run the same distance! Where do you see circles and semicircles in the world around you? Why could finding the area or circumference be helpful?