Math Salamanders Ltd.
2D Shape Sheet Rectangle
In this 2D shape/rectangle worksheet, students view a picture of a large rectangle. The worksheet has no other associated activities, but a reference website provides additional activities.
Sophia Learning
Sophia: Using Triangles to Find the Sum of Interior Angles: Lesson 1
This lesson demonstrates how to use triangles to determine the sum of the interior angles of a polygon. It is 1 of 5 in the series titled "Using Triangles to Find the Sum of Interior Angles."