Students make any quadrilateral on the geoboard. They then transfer the quadrilateral onto the geodot paper twice. Students measure the angles of the quadrilateral and mark both copies of the quadrilateral.


Students leave one of the quadrilaterals as it is. They cut out the angles of the other quadrilateral and rotate the angles around one point, as shown above.

When students add up the angles, they realize the interior angles of all quadrilaterals add up to 360°.


Here are some examples from Mr. Greenman's class which illustrate that the interior angles of any quadrilateral add up to 360°:

Download Geodot Paper	Online Geoboard

Indicators

3.5.2.1 use protractors to measure angles.

2.5.1.1 identify, describe, compare, and classify two- and threedimensional figures by relevant properties including the number and size of angles, the number of vertices, the number of edges, and the shapes of the faces

2.6.1.1 use a variety of triangles and quadrilaterals to draw conclusions about the sum of the measure of their interior angles. .