Site: Ricci Adams’ musictheory.net

Ricci Adams’ musictheory.net is not only the best online resource available for learning and reinforcing basic music theory, it is probably the best single tool available for that purpose anywhere. And it’s free.

Lessons and drills are all Flash-based, so you must have Macromedia’s plugin for your browser. However, the benefits are many; the pages load quickly, the lessons are both clear and aesthetically pleasing, and it provides a web based platform to present the training modules.

Site offerings are split into three categories: Lessons, Trainers, and Utilities. The former offers theory instruction from the absolute basics to more advanced topics like Neapolitan chords and Analysis. Trainers include drills on the notes in the staff, intervals, and triads, and also offer instrument specific drills for Keyboard, Guitar and Trumpet. Utilities include a matrix generator for tone rows, a chord calculator, and a staff paper generator.