Scale degrees and their names – free music theory course

Each note of a scale is a degree, numbered I to VII in Roman numerals (or with careted numbers 1̂–7̂). Each has a name and, more importantly, a role: some are resting points, others are tension notes that "want" to go somewhere.

Degree	Name	In C major	Role
I	tonic	C	the centre, "home"
II	supertonic	D	just above the tonic
III	mediant	E	halfway between tonic and dominant; decides major vs minor
IV	subdominant	F	a fifth below the tonic; leans down to III
V	dominant	G	the second pillar, calls for a return to the tonic
VI	submediant	A	halfway down from tonic to subdominant
VII	leading tone (leading note)	B	a half step below the tonic: strongly drawn to it

When degree VII lies a whole step below the tonic (as in the natural minor scale), it loses its pull and is called the subtonic.

M:4/4
L:1/4
Q:1/4=80
K:C
C D E F | G A B c |]
w: I II III IV V VI VII I

Tendencies

Listen: stop on the leading tone (B) and your ear demands C. It is the strongest pull in tonal music.

M:4/4
L:1/4
Q:1/4=72
K:C
C E G B | c4 | c B A G | F2 E2 | D B, D2 | C4 |]

Stable degrees: I, III, V (the notes of the tonic chord).
Unstable degrees: VII → I (up a half step), IV → III (down a half step), II → I, VI → V.

Thinking in degrees is thinking like a musician: a "3-2-1" melody tells the same story in every key. That is the principle of movable do (do-re-mi sung on scale degrees whatever the tonic) and of Roman-numeral chord analysis (I-IV-V-I), which you will meet in part two of the course.

Mind the names: "subdominant" does not mean "just below the dominant" but "the dominant underneath": IV is a fifth below the tonic, just as V is a fifth above.