Polygon Sum of Interior Angles

① This GeoGebra example dynamically demonstrates how the sum of interior angles of a polygon changes as the number of sides varies. ② The core mathematical concept is the polygon interior angle sum formula (n-2)×180°, involving angle measurement, polygon classification, and geometric reasoning. ③ Construction highlights: uses the Polygon command to create poly1, the Angle command to mark interior angles (α, β, etc.), a slider or variable n to control the number of sides, and text1 to display the current angle sum in real time; all vertices (A, B, C, …) are draggable to alter the shape. ④ Suitable for middle school geometry classes or high school review, helping students understand the derivation of the angle sum formula, explore differences between convex and concave polygons, and develop dynamic geometric thinking.