Mathigon
Mathigon: Geometry: Polygons and Polyhedra: Polygons
This lesson focuses on polygons; a polygon is a closed, flat shape that has only straight sides. Polygons can have any number of sides and angles, but the sides cannot be curved.
Cuemath
Cuemath: Concave Shapes
A comprehensive guide for learning all about concave shapes with definitions, the difference between concave and convex, examples, and practice questions.
Sophia Learning
Sophia: Sum of Angles in Polygons
This tutorial with video and slideshow components investigate the characteristics of polygons as well as how to calculate the interior and exterior angles of any polygon. It offers two PowerPoint presentations and two videos that feature...
Math Open Reference
Math Open Reference: Polygons
Get the definition and properties of a polygon. Then explore such topics as: 1) types of polygon 2) area 3) Perimeter 4) angles associated with polygons and 5) names of polygons.
CK-12 Foundation
Ck 12: Geometry: Polygons Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide focuses on polygons: convex vs concave, interior and exterior angles, and basic terminology for common polygons.
CK-12 Foundation
Ck 12: Geometry: Polygon Classification
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to classify a polygon based on its sides and how to determine whether a polygon is convex or concave.
Sophia Learning
Sophia: Classifying Polygons
This lesson explores the characteristics of various types of polygons. It includes two PowerPoint presentations that test students' understanding by grouping polygons in the correct categories.
CK-12 Foundation
Ck 12: Interactive Geometry: 1.3 Polygons
Explore the structure and measurement of polygons.
Cuemath
Cuemath: Convex Shapes
A comprehensive guide for learning all about convex shapes with definitions, examples, and practice questions.
The Math League
The Math League: Figures and Polygons
This website has basic definitions for most polygons, regular and irregular.
Math Open Reference
Math Open Reference: Irregular Polygon
A complete reference guide to irregular polygons. It provides definitions and an interactive activity that enhances further explanation. Includes links to related topics.
ClassFlow
Class Flow: Polygons
[Free Registration/Login Required] This flipchart defines a polygon and the classification of concave and convex polygons.
Ducksters
Ducksters: Kids Math: Polygons
Polygons for kids. Learn how they work, terms, tricks and examples. Regular, convex, concave, complex, and more.
National Council of Teachers of Mathematics
The Math Forum: Plane Figure
This site provides a definition for plane figure (at the top of the page) and a few examples.
University of Georgia
University of Georgia: Inter Math: Nonagon
This site gives the general definition of a nonagon with examples of a regular (convex) and irregular concave nonagons. There are links to related terms, challenging problems, more information, and the interactive check point involving...