Interactive
National Council of Teachers of Mathematics

Nctm: Illuminations: Angle Sums

For Students 9th - 10th
Students may use this computer applet to explore angle sums of triangle, quadrilaterals, pentagons and hexagons.
Lesson Plan
OER Commons

Oer Commons: Exploring Polygons

For Teachers 6th - 8th
In this lesson, students explore different polygons by drawing them, measuring angles, and manipulating interactive sketches to find the angle sum for any polygon. Students also explore the angle measures in regular polygons. Included...