Other
Music Theory First Aid for Struggling Students
This site provides music theory information on such topics as rhythm, intervals, scales, chords, etc. Also, there is a fine section which describes the basic concepts of form and structure.
Other
Tone Savvy: E Music Theory
This site provides good online learning games and exercises for music theory. It also has a lot of options for teachers if they choose to subscribe.
Music Theory
Music theory.net
An online beginning music theory and ear training site. This site is for students to use at home to reinforce what they learn in class.