Lesson 5: Triads: Building Chords from the Scale

A chord is three or more notes played together. The simplest and most common chord is a triad - three notes stacked in thirds, meaning you take a note, skip one, take the next, skip one, take the next. Triads are built directly out of a scale, using exactly the tools you already have: scale degrees and intervals.

Take the C major scale from Lesson 3 and stack thirds starting on its first degree: C, skip D, take E, skip F, take G. That gives you C, E, G - a C major triad. The bottom note is called the root, the middle note is the third, and the top note is the fifth.

A triad's quality - whether it sounds major, minor, diminished, or augmented - depends on the exact size of the two stacked thirds, using the major/minor third intervals from Lesson 2. Stack a major third then a minor third and you get a major triad. Stack a minor third then a major third and you get a minor triad.

Two more triad qualities exist, both less common but worth knowing. A diminished triad stacks two minor thirds in a row, which makes it sound tense and unstable. An augmented triad stacks two major thirds in a row, which makes it sound unsettled in a different way - neither quite resolves the way a major or minor triad does.

Every triad you'll ever encounter - in any key, on any instrument - is one of these four qualities. Next lesson: chords rarely sit still. They move from one to another in patterns called progressions, and those patterns end with specific two-chord punctuation marks called cadences.