Splitting a scale into lower (1–4) and upper (5–8) tetrachords reveals how modes relate. Swapping tetrachords shifts modal color without losing the tonal center. Every major, minor, or modal scale can be thought of as two stacked tetrachords:
- Lower tetrachord: 1–2–3–4 (C-D-E-F)
- Upper tetrachord: 5–6–7–1 (G-A-B-C)
Why They are Useful
- You can swap lower or upper tetrachords to change the mode without losing the tonal center.
- Stable notes like root, 4th, and 5th help keep your melody grounded while you experiment.
- They let you hear modal color shifts in small, manageable chunks rather than memorizing full scales.
Shapes
There are 4 different shapes. Learn each of them with different starting fingers.
| Tetrachord | Formula | Notes from C | Diagram |
|---|---|---|---|
| Major (Ionian) | R-W-W-H | C D E F |  |
| Minor (Dorian) | R-W-H-W | C D E♭ F |  |
| Upper Minor (Phrygian) | R-H-W-W | C D♭ E♭ F |  |
| Whole Tone (Lydian) | R-W-W-W | C D E F♯ |  |
Combining Shapes
We can combine tetrachords to create all the Modes. Red is the first note in the lower tetra chord, blue is the first note of the upper tetrachord. Here are some patterns. Try out different starting fingers!
| Scale | Tetrachords | Diagram |
|---|---|---|
| Ionian | Major + Major |  |
| Dorian | Minor + Minor |  |
| Phyrigian | Upper Minor + Upper Minor |  |
| Lydian | Whole Tone + Major |  |
| Mixolydian | Major + Minor |  |
| Aeolian | Minor + Upper Minor |  |
| Locrian | Upper Minor + Lydian |  |
Ascending/Descending
Notice how the lower/upper tetrachord revolves around the root.
Ionian Scale
Practice
N Notes per String
Play across strings
- Full tetrachord on a single string
- 3 notes on upper string, 1 note on lower string
- 2 notes each string
- 1 note on upper string, 3 notes on lower string
More
- Create Modes by swapping tetrachords
- In a ii–V–I, swap only the upper tetrachord on the V chord for color
- Target guide tones (3rd and 7th) within each tetrachord