Scales and Keys · Lesson 2
The Three Minor Scales
about 15 min
What this lesson is for
There are three minor scales because what harmony demands and what a singable melody wants came into conflict. Starting from natural minor, this lesson follows the actual order of events - why the seventh degree had to be raised, and how the awkward interval that created was then engineered away.
- Describe natural minor by its differences from major - lowered third, sixth, and seventh
- Explain the reason harmonic minor exists, which is the need for a leading tone
- Identify the augmented 2nd between degrees 6 and 7 of harmonic minor
- Explain why melodic minor takes different forms ascending and descending
In this lesson
There is one major scale but three minor scales. This is usually the first point at which music theory starts to feel like arbitrary bookkeeping. It is not: the reasons are clear, and they arrived in a definite historical order.
The short version is that what harmony demanded and what melody wanted turned out to conflict. The three scales are the surviving record of how that conflict was settled.
Start with natural minor
Natural minor is the starting point, and it can be defined as a major scale with degrees 3, 6, and 7 each lowered by a half step.
| Degree | Major | Natural minor |
|---|---|---|
| 3 | major 3rd | minor 3rd |
| 6 | major 6th | minor 6th |
| 7 | major 7th | minor 7th |
Its interval sequence is whole – half – whole – whole – half – whole – whole.
A minor works on white keys because it draws on the same collection of pitches as C major. Two keys that share a pitch collection but differ in tonic are called relative keys, which is why they share a key signature as well — in this case, no accidentals at all.
Why do identical notes produce a different scale? Because which note is heard as home is different. Center the music on A and it is minor; center it on C and it is major. A scale is not determined by its collection of pitches but by each pitch’s relationship to the tonic.
One pitch collection, two tonics
Check: The first runs the seven white keys from C, the second from A. The notes are literally identical, so listen for how completely the bright/dark impression flips. The third adds an A minor chord after landing on A, which makes the sense of A as home even more definite.
bright
The harmonic problem — there is no leading tone
Natural minor has a weakness once you start harmonizing it. Its seventh degree sits a minor 7th above the tonic, which leaves a whole step to travel to reach home.
The previous lesson traced the major scale’s strong sense of arrival to the half step pull from degree 7 into the tonic. Natural minor does not have that, and its cadences are correspondingly weak.
Concretely, the trouble shows up in the chord built on the fifth degree. Stacking a triad on E in A minor gives E–G–B, which is E minor. Where major has a bright major triad on V with real pulling power, minor gets a limp one.
What a leading tone does to a cadence
Check: The first is v to i straight out of natural minor (Em to Am). The second raises the seventh degree to give V to i (E major to Am). The second lands unmistakably harder — and that difference is the entire reason harmonic minor was invented.
Em → Am. The arrival is weak
First fix: harmonic minor
The response was to raise only the seventh degree by a half step. That gives harmonic minor, and the name records exactly where the pressure came from.
That restores the leading tone, turns V into a major triad, and makes strong cadences available again. Whenever you see a minor-key score peppered with accidentals the key signature never declared, it is almost always this raised seventh — which is what the previous unit meant by calling it a reliable clue for identifying a minor key.
But it creates an augmented 2nd
There is a side effect. The gap between the sixth degree (F) and the raised seventh (G♯) is now three half steps. The letters are only F and G, so it counts as a 2nd, and one half step wider than a major 2nd makes it an augmented 2nd.
Augmented 2nds are hard to sing. Unit 5 covers this in detail, but part-writing convention treats melodic motion by an augmented interval as forbidden. So solving the harmonic problem introduced a melodic one.
The same interval also has a striking, distinctly exotic sound, and plenty of music from the Middle East and from Spanish traditions uses it deliberately. It returns later in this unit, in the lesson on Japanese and Asian scales, in a scale that contains two of them.
Check
In C harmonic minor, which two notes form the augmented 2nd?
Second fix: melodic minor
How do you get rid of that augmented 2nd? By raising the sixth degree as well. With the sixth raised, the gap between 6 and 7 returns to a whole step and the line smooths out.
That gives melodic minor — with one ingenious extra provision. Its ascending and descending forms differ.
- Ascending: raise degrees 6 and 7 (this is the direction that needs a leading tone)
- Descending: revert to natural minor (coming down, no leading tone is required)
Coming down, the F♯ and G♯ are abandoned in favor of F and G. That makes it a single scale that uses different notes depending on the direction of travel — a structure with no parallel elsewhere in the system.
The accurate way to read this odd shape is as a negotiated settlement between two demands: harmony wants a leading tone, melody wants no augmented 2nd. It was not deduced from first principles; it was found in practice and then written down.
The three scales back to back
Check: First natural minor, then harmonic minor (seventh degree raised, with the augmented-2nd leap between degrees 6 and 7), then ascending melodic minor (sixth raised too, so the line runs smooth). Listen for the catch in the second one and for its disappearance in the third.
no leading tone
Check
The descending form of melodic minor is identical to which scale?
In practice all three get mixed
An important qualification. Real pieces are not written “in harmonic minor.” All three forms appear inside the same piece, chosen situation by situation.
- building a chord, especially V → raise the seventh
- a melody moving stepwise from degree 6 up to degree 7 → raise the sixth as well
- a descending line, or a passage that wants to stay dark → leave both alone
So what a minor key actually is, in practice, is not “one of three scales” but a key whose sixth and seventh degrees move up and down as circumstances require. The three-way classification is best understood as a teaching device for that variability rather than as three separate objects.
That variability matters directly when the diatonic chords of minor keys come up in a later unit. The reason a minor key can support two different chords on the same degree — both v and V exist — traces back to exactly this movable seventh.
Switch between the three and listen Toggle natural, harmonic, and melodic minor in the scale dictionary. Watching which keys change in the highlighting makes it concrete that the difference is only one or two notes Scale Dictionary → Take an early look at the chords of a minor key V appears as a major triad because the tool is using harmonic minor with its raised seventh. Unit 3 takes this up properly Diatonic Chord Reference →Exercises
Every answer here is cross-checked against the theory engine. Work them out before you grade.
- 1
Spell the seven notes of the A natural minor scale from the tonic upward, using single spaces between names.
- 2
Spell the seven notes of the C harmonic minor scale from the tonic upward, using single spaces between names.
- 3
What is the interval between the sixth and seventh degrees of a harmonic minor scale?
- 4
Melodic minor takes different forms going up and coming down. What two requirements is that reconciling?
- 5
Compared with the major scale, which degrees are lowered in natural minor?
Before you move on
Check that you can explain each point above in your own words.