Why was the obtuse angle upset? Because it was never right! A valuable resource is loaded with background information on types of angles and lines. Learners review the characteristics of parallel, perpendicular, and...

Looks at the lines of symmetry in different types of polygons. Includes ten practice questions. Each question is accompanied by an explanation of the answer.

Explains the terms and symbols used to discuss line angles, what an angle is, and the types of angles. Includes short video lesson demonstrating how to use a protractor to measure an angle. [0:57]

This tutorial provides an explanation and example of parallel lines.

This tutorial gives a very basic definition of lines.

This tutorial provides an explanation of line segments.

Geometry lesson on line symmetry with practice exercises.