Definition and properties of adjacent angles  those that share a common leg or ray
Math Open Reference

Definition of an angle.
Math Open Reference

This website is a worksheet to estimate and measure angles. The answer sheet is there also.
MathDrills.com

Worksheet with right angle questions and answers.
Helping with Math

Explanation and examples of angles along a straight line.
Math is Fun

Explanation and example of angles around a point.
Math is Fun

This page goes through the definitions and then some practice problems for identifying them
Homeschool Math

A site that goes through general descriptions of angles and the types of angles, but includes additional interactive construction demonstrations.
Hamilton's Math to Build On!

Basic overview of supplementary angles
Math is Fun

Definition of an acute angle (one less than 90 degrees).
Math Open Reference
