Scales, keys and a sense of home

Major is a pattern of distances

In the first chapter you moved intervals without changing their size. You can move a major scale the same way. Its steps are 2–2–1–2–2–2–1 semitones.

From C this gives C–D–E–F–G–A–B–C. From G it gives G–A–B–C–D–E–F♯–G. Raising F to F♯ preserves the final whole step and half step. Black keys help keep the pattern intact; they are not exceptions to it.

Give each note a scale degree

Count from the start of the scale: in C major, C is degree 1, D is degree 2 and E is degree 3. The next C is degree 1 again, an octave higher. In G major, G is degree 1 and A is degree 2. Degrees describe relationships rather than fixed keys on the piano.

We will use Roman numerals for chords built on these degrees. For now, find the first, third and fifth scale notes: in C major they are C, E and G.

The same notes can have a different home

Play the white keys from A to A: A–B–C–D–E–F–G–A. This is A natural minor. Its steps are 2–1–2–2–1–2–2, so the pattern from A differs from the major pattern from C. The distances from A are 0, 2, 3, 5, 7, 8 and 10 semitones.

C major and A natural minor share seven pitch classes but have different tonal centres. They are relative keys. A is three semitones below C. Do not confuse relative keys with parallel keys: C major and C minor are parallel because they share the same tonic.

A key is more than a starting note

A scale puts a set of notes in order. A key also involves a feeling of home, centred on a note called the tonic. Starting a melody on A does not automatically put it in A minor. Accents, bass notes and endings help establish the centre.

Minor-key music does not use only natural minor. A minor also often uses G♯, a semitone below A, to lead clearly towards it. Raising degree 7 this way gives harmonic minor. Other forms, including melodic minor and modes, expand the possibilities; here we focus on major, natural minor and the sense of a centre.

Try it at the piano

Listen to C major and G major below. Find F♯ in the second scale. Then play white keys over a repeated low C and end on C. Repeat with A in the bass and end on A. A scale alone does not establish a key; listen to how the bass and ending influence the sense of home.