Scales, Keys, and Intervals: every key term you need (+ practice quiz)

More AP Music Theory guides

• Triads and Seventh Chords
• Harmonic Function and Voice Leading
• Harmonic Progressions and Cadences
• Secondary Function, Modulation, and Form

Major Scale

Seven-note scale with the pattern W–W–H–W–W–W–H; half steps fall between scale degrees 3–4 and 7–8.

Natural Minor Scale

Minor scale with the pattern W–H–W–W–H–W–W; identical to the Aeolian mode.

Harmonic Minor Scale

Natural minor with a raised 7th degree, creating a leading tone and an augmented 2nd between 6̂ and 7̂.

Melodic Minor Scale

Minor scale with raised 6th and 7th degrees ascending; traditionally reverts to natural minor descending.

Key Signature

Sharps or flats written after the clef that apply throughout, defining the key; sharps add in the order F–C–G–D–A–E–B.

Circle of Fifths

Arrangement of the 12 keys by ascending fifths; each clockwise step adds one sharp (C→G→D), each counterclockwise step adds one flat.

Relative Keys

A major and minor key sharing the same key signature; the relative minor's tonic is scale degree 6 of the major (C major / A minor).

Parallel Keys

A major and minor key sharing the same tonic but different signatures, like C major and C minor.

Tonic (1̂)

The first scale degree; the tonal center and point of rest.

Supertonic (2̂)

The second scale degree, a step above tonic.

Mediant (3̂)

The third scale degree, midway between tonic and dominant.

Subdominant (4̂)

The fourth scale degree, a fifth below tonic.

Dominant (5̂)

The fifth scale degree; harmonically the strongest pull toward tonic.

Submediant (6̂)

The sixth scale degree, midway between tonic and subdominant (counting downward).

Leading Tone (7̂)

The raised seventh degree, a half step below tonic, with a strong tendency to resolve upward to 1̂.

Subtonic

The seventh degree of natural minor, a whole step below tonic (lowered 7̂); lacks the leading tone's upward pull.

Interval Number

The count of letter names spanned by two pitches, inclusive: C up to G spans C-D-E-F-G, a fifth.

Interval Quality

The precise size of an interval: perfect, major, minor, augmented, or diminished.

Perfect Intervals

Unison, 4th, 5th, and octave; they are perfect, never major or minor. Altering a perfect interval by a half step makes it augmented or diminished.

Major and Minor Intervals

2nds, 3rds, 6ths, and 7ths; a major interval shrunk by a half step becomes minor.

Augmented Interval

An interval one chromatic half step larger than perfect or major, such as C–F♯ (augmented 4th).

Diminished Interval

An interval one chromatic half step smaller than perfect or minor, such as B–F (diminished 5th).

Tritone

The interval of three whole steps — an augmented 4th or diminished 5th — dividing the octave exactly in half; historically unstable.

Interval Inversion

Flipping an interval so the lower note moves above; numbers sum to 9 and qualities swap (major↔minor, aug↔dim), perfect stays perfect.

Compound Interval

An interval larger than an octave, like a major 9th; functionally equivalent to its simple counterpart (a major 2nd).

Consonance and Dissonance

Consonant intervals (3rds, 6ths, perfect 5ths/octaves) sound stable; dissonances (2nds, 7ths, tritone) demand resolution.

Chromatic Scale

Scale of all twelve half steps; ascending motion is conventionally spelled with sharps, descending with flats.

Pentatonic Scale

Five-note scale; the major pentatonic omits scale degrees 4 and 7 of the major scale.

Whole-Tone Scale

Six-note scale built entirely of whole steps, with no half steps and no leading tone.

Dorian Mode

Mode starting on scale degree 2 of a major scale; minor-sounding with a raised 6th (D to D on white keys).

Phrygian Mode

Mode starting on scale degree 3 of a major scale; minor-sounding with a lowered 2nd (E to E on white keys).

Lydian Mode

Mode starting on scale degree 4 of a major scale; major-sounding with a raised 4th (F to F on white keys).

Mixolydian Mode

Mode starting on scale degree 5 of a major scale; major-sounding with a lowered 7th (G to G on white keys).

Scale Degree Solfège

Movable-do syllables for degrees 1–7: do, re, mi, fa, sol, la, ti; minor commonly uses do-based with me, le, te.

Transposition

Rewriting music at a different pitch level while preserving all interval relationships and the key's structure.