Shapes and their Insides

The purpose of this task is to help students differentiate between a polygon and the region inside of a polygon so that they understand what is being measured when the perimeter and area are being found. A polygon is a figured composed of line segments that meet end-to-end, forming a simple closed curve. A polygon always divides the plane into exactly two regions - one 'inside' the polygon and one 'outside.' In order to understand perimeter as an attribute of a plane figure, students need to be able to pick out the part of a figure that is being measured when finding perimeter.