1. Scale Degrees — the key’s numbered alphabet
Every major key is built from a fixed pattern of steps (whole step = 2 keys apart on piano including black keys, half step = 1 key apart):
Whole, Whole, Half, Whole, Whole, Whole, Half
Apply that starting on C (easiest key — no black keys involved) and you get the C major scale. Number the notes 1 through 7:
| Scale degree | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| Note (C major) | C | D | E | F | G | A | B |
That’s it — this is just the key’s own numbered vocabulary. Every chord in the key is built from these seven notes only.
Try it: play C-D-E-F-G-A-B-C slowly with your right hand, saying the numbers out loud as you go.