21.2 · Sevenths & Jazz

A 7th on every step

Build a four-note chord on every step of C major, using only scale notes. The scale hands each step its own quality. No choices to make, the key decides. This is the chord set jazz tunes are written in.

The key, upgraded

One seventh chord on each of the seven steps. The colors are the same roles as the triads; each chord just carries one more note.

Home note · sets the key

The seven 7ths of C major

The pattern is fixed in every major key: maj7 · m7 · m7 · maj7 · 7 · m7 · ø7. Only one step gets the dominant quality (V), and only one gets half-diminished (vii).

Triad vs. seventh, side by side

Each pair is the same chord as a triad, then as a 7th. The role doesn't change; the voice does.

Game · Name the step

1 / 6

The home note, then one of the key's seven 7ths, broken and together. Which step is it?

Listen first. Then answer.

Quiz

1 / 3

In any major key, which step carries the dominant 7th quality?

Score 100% on every quiz and game to complete this lesson. A perfect run sticks: a later miss never undoes it.The ii–V–I →