Music Theory
Music theory.com: Introduction to Chords
A description of augmented and diminished triads/ chords. Provides illustrated examples with highlighted vocabulary words,a printable chart, and audio clips to supplement the lesson.
Music Theory
Music theory.net: Chord Ear Trainer
This online quiz gives students a chance to recognize triads and seventh chords, by listening to audio clips. Teachers can customize this quiz and print out progress reports.
OpenStax
Open Stax: Catherine Schmidt Jones: Naming Triads
Learn about the various types of triads. This lesson focuses on the chords in root position. Included in this site are a few self checking tests.
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.