www.teoria.com is a fantastic, free, interactive website designed to teach music theory.  Developed by José Rodríguez Alvira of the Conservatory of Music of Puerto Rico, the site offers a broad range of music theory tutorials and exercises.  Beginning to advanced music theory students will find the site informative and interesting.

The site uses musical notation, keyboard, and audio clips to represent and demonstrate music theory concepts, which include how to read music, intervals, scales, chords, harmonic functions, and musical forms.  The sites’ exercises offer interactive lessons in ear training, music theory and music reading skills.