02 · Musical Building BlocksLesson 4 of 17About 6 minutes
What you’ll learnWhat musical relationship does Scale Degree Positions reveal, and how can you recognise it?
The Rectangle · Lesson 4
7 | Scale Degree Positions
The Rectangle identifies the four core major-key relationships instantly: I, IV, V, and vi.
Lesson 7Four Chord Trick
Select a major tonic — relationship strip
Choose a tonic. The Rectangle immediately gives IV = T − 1, V = T + 1, and vi = T + 3.
I = TIV = T−1V = T+1vi = T+3
Enharmonic pairs share the same sound but use different spellings: Gb = F#, Db = C#, and Cb = B.
Relationships
I
T
Tonic
IV
T − 1
Subdominant
V
T + 1
Dominant
vi
T + 3
Relative minor
Scale degree map
Keyboard relationship map
Blue = I · Orange = IV · Green = V · Purple = vi
Core theory
I = T
Tonic / home chord
IV = T − 1
Subdominant
V = T + 1
Dominant
vi = T + 3
Relative minor / minor sixth