Classifying polygons

In this lesson, we will learn:

• How to name polygons: triangles, quadrilaterals, pentagons, hexagons, heptagons, and octagons
• How to classify regular vs. irregular polygons
• How to read markings on polygons: hashmarks for congruent sides, semicircles for congruent angles, arrows for parallel sides, and squares (right angles) for perpendicular sides

Notes:

• Polygons are 2D shapes with straight sides only. All polygons have sides (straight lines/edges) and vertices (corners/points where sides meet).


• Polygons are named by the number of sides they have:

• Polygons can be regular or irregular. Regular polygons have congruent sides and angles; all sides and all angles are equal. Irregular polygons do not have same size sides and angles.

• Congruent sides can be shown with hashmarks (matching lines on the sides that are equal)
• Congruent angles can be shown with either semicircles with hashmarks, or with concentric circles