Instructional Video
Khan Academy

Khan Academy: Classifying Shapes by Lines and Angles

4th - 5th Standards
Demonstrates how to find what 2D shape matches a set of properties. [3:37]
Instructional Video
Loyola University Chicago

Math Flix: Polygons

3rd - 8th Standards
This video [4:39] provides an opportunity to learn about the characteristics of polygons. As you watch and listen to the teacher and student interact it helps clarify the thinking behind applying this concept.
Instructional Video
Khan Academy

Khan Academy: Classifying Shapes by Line and Angle Types

4th Standards
Explains how to classify 2D shapes based on the properties of their sides and angles. [2:15]