Here is a site that clearly and thoroughly explains many topics regarding measurement of angles, including standard position, degree measure, and coterminal angles. There are example problems solved, problems for the student to attempt,...

Convert angle measures given in degrees to radians and vice versa.

This site offers a discussion on radian measure. The site offers pictures and explanations to clarify the formulas given. (Note: The free download at the end of the page will not work in archived version of site.)