Decompose an athletic track
Change a stadium shape and watch its area decompose into one rectangle plus one full circle.
A running track is a rectangle plus two half-circles. Two halves stitch into one whole circle, so the track area = rectangle + circle. Composite figures don't need new formulas — they need decomposition.
Aligned with CCSS 7.G.B.4.
Two semicircles combine into one full circle plus a rectangle.
Geometry and measurement model
Stadium-Shape Area is built for students who memorize formulas before seeing the shape decomposition. It gives the page a clear search purpose: learn the model, manipulate it, then continue into the matching grade-level practice.
Stadium-Shape Area helps when a student can copy a procedure but cannot explain why it works. The demo slows the idea down into a visible model before sending the learner to guided missions.
Learning goals
How to play
Continue with guided practice
Split into a rectangle and two half-circles. Two halves of equal radius = one full circle. Stadium area = (length × straight width) + πr².
Two straight edges + the full circumference of the stitched-together circle. Perimeter = 2 × straight + 2πr.
Because composite figures rarely have a single formula. Splitting into known shapes (rectangles, circles, triangles) reduces hard problems to easy parts.
Grades 6–7, aligned with CCSS 7.G.B.4. Strong example of "decompose then add."
