What is a Polygon? Dr. Beth McCulloch Vinson Athens State University PT3 Grant Funding, Summer 2000

A polygon is… a many-sided figure a shape with three or more sides.

What do we need to know about polygons? How many sides does each polygon have? Do all polygons look the same? Can I know the name of a shape just by looking at it?

A triangle has three sides. 1 3 2

Square A square has four sides. 4 3 1 2

A pentagon has five sides. 1 5 2 4 3

Hexagon and Heptagon A hexagon has six sides. (Hexagon and six both have an “x”.) A heptagon has seven sides. heptagon hexagon

Octagon An octagon has eight sides. Count the sides. If this octagon was red and had the word “Stop” written on it, then you would know where we see a lot of octagons.

Let’s Review: The triangle is the smallest polygon. It only has three sides. A pentagon has five sides. A hexagon has six sides. A heptagon has seven sides. An octagon has eight sides.

Match these. Triangle eight sides Heptagon three sides Octagon seven sides

Match some more. Pentagon four sides Hexagon five sides Square six sides

Key Question: A triangle is the smallest polygon because it has three sides. Can you have a two-sided polygon? Why or why not? Two lines don’t close to make a shape. They make an angle. 1 2

Preparing Tomorrow’s Teachers to Use Technology (PT3) The END A Project Developed for Preparing Tomorrow’s Teachers to Use Technology (PT3) By Dr. Beth McCulloch Vinson Athens State University, School of Education http://www.athens.edu/vinsobm