What do you create when you rotate a ray? An angle! Teach all the angle basics including naming, measuring, supplements, and complements. 

Geometry is full of shapes, figures, and corresponding things here and there. The guide shares all of the key pieces of geometric information in a nicely color-coded and labeled sheet. 

Everything you wanted to know about angles and more, including 1) how to measure angles 2) types of angles 3) angle relationships and 4) angles around a transversal.

Intermath Dictionary's site defines terms relating to angles, gives examples, and offers interactive exercises.

A complete reference guide to vertical angles. It provides definitions, examples, and an interactive activity that enhances further explanation. Includes links to related topics.

A list of geometry definitions and a matching activity.