Construct major and minor scales using tone and semitone patterns, identify key signatures up to four sharps and flats, and recognise relative and tonic relationships

What this dot point is asking

SEAB wants you to build major and minor scales from their tone and semitone patterns, to read and write key signatures up to four sharps and four flats, and to recognise the relationships between keys, especially the relative and tonic minor. The central insight is that a key is a pattern, not a list to memorise: once you know the major pattern and the three forms of the minor, you can construct any scale and read any signature by counting.

The answer

The major scale pattern

A major scale is a fixed sequence of tones (T, a whole step) and semitones (S, a half step):

Starting on C and applying this gives C, D, E, F, G, A, B, C, all white notes, with semitones between E and F and between B and C. Start the same pattern on any note and you get that major scale.

The three minor scales

Minor keys come in three forms, all sharing the same key signature:

• Natural minor uses only the notes of the key signature.
• Harmonic minor raises the seventh degree by a semitone (both up and down) to create a leading note, producing a distinctive augmented-second gap.
• Melodic minor raises the sixth and seventh degrees ascending, then lowers both again descending.

Key signatures and the circle of fifths

A key signature is the set of sharps or flats written at the start of each line, applying throughout. The keys are organised in the circle of fifths: each step clockwise adds one sharp (and moves the tonic up a fifth), each step anticlockwise adds one flat. Up to four accidentals:

• Sharp keys: G (1), D (2), A (3), E (4).
• Flat keys: F (1), B flat (2), E flat (3), A flat (4).

The order in which sharps appear is F, C, G, D; flats appear in the reverse order, B, E, A, D.

Relative and tonic minor

Every major key shares its signature with a relative minor whose tonic is a minor third (three semitones) below the major tonic: C major and A minor share no sharps or flats, D major and B minor share two sharps. The tonic minor has the same tonic note but a different signature: C major and C minor start on the same C but C minor has three flats.

Examples in context

Example 1. A change of mood from major to minor. A composer who restates a cheerful major-key theme in the tonic minor instantly darkens its character while keeping the same starting note. Recognising this shift, hearing the lowered third, sixth and seventh, is a common listening task that depends on knowing the tonic-minor relationship.

Example 2. Modulation to the dominant. Many Classical pieces move from the home key to the dominant (a fifth higher) for contrast, which on the page means a new sharp appears in the music. Tracking added or cancelled accidentals against the circle of fifths is how you follow such a modulation.

Try this

Q1. Write the tone-and-semitone pattern of a major scale and use it to build E major. [3 marks]

• Cue. The pattern is T, T, S, T, T, T, S; from E this gives E, F sharp, G sharp, A, B, C sharp, D sharp, E (four sharps).

Q2. Explain how the harmonic minor differs from the natural minor. [2 marks]

• Cue. The harmonic minor raises the seventh degree by a semitone, both ascending and descending, to create a leading note, which the natural minor lacks.

Q3. Name the relative minor of B flat major and state why they are related. [2 marks]

• Cue. The relative minor is G minor; it lies a minor third below B flat and shares the same two-flat key signature.