Identify, construct and notate intervals, major and minor scales, modes and their key signatures as part of music literacy

What this dot point is asking

SCSA wants you to read, build and write the basic raw material of tonal music quickly and without error. In the aural and theory paper these skills underpin dictation, harmony and analysis, so they need to be automatic rather than worked out from scratch each time.

Intervals

An interval has two parts: a size (a number) and a quality (a word).

The size is found by counting letter names inclusively from the lower to the upper note. From C up to G is a fifth (C, D, E, F, G is five letters). The size ignores sharps and flats; only the letter names are counted.

The quality describes the exact distance in semitones:

• Unisons, fourths, fifths and octaves can be perfect, augmented or diminished.
• Seconds, thirds, sixths and sevenths can be major, minor, augmented or diminished.

A major interval made one semitone smaller becomes minor; a minor made one smaller becomes diminished. A perfect or major made one semitone larger becomes augmented. Worked counting in semitones is the reliable method: a major third is 4 semitones, a perfect fifth is 7, a minor seventh is 10.

Major and minor scales

A major scale follows the fixed tone and semitone pattern T T S T T T S. Starting on C this gives C D E F G A B C with no sharps or flats. Starting on any other note, accidentals are added to keep that exact pattern.

Minor scales come in three forms built on the same key signature as their relative minor:

• Natural minor uses the key signature unchanged (pattern T S T T S T T).
• Harmonic minor raises the seventh degree by a semitone, creating the leading note and the distinctive augmented second between the sixth and seventh.
• Melodic minor raises both the sixth and seventh ascending, then lowers both to the natural form descending.

The relative minor of a major key starts on the sixth degree of that major scale; A minor is the relative minor of C major. The parallel minor shares the same tonic but a different key signature; C minor is the parallel minor of C major.

Modes

Modes are scales built on each degree of the major scale using the same notes but a different starting pitch. The white-note modes are a quick reference: Ionian (C, the major scale), Dorian (D), Phrygian (E), Lydian (F), Mixolydian (G), Aeolian (A, the natural minor) and Locrian (B). Modes appear often in jazz and contemporary contexts, so recognising Dorian and Mixolydian by ear and on the page is worth practising.

Key signatures and the circle of fifths

A key signature is the group of sharps or flats written after the clef that applies for the whole piece. They are written in a fixed order:

• Sharps: F C G D A E B.
• Flats: B E A D G C F (the reverse).

The circle of fifths organises keys by adding one sharp for each step clockwise (a fifth up) and one flat for each step anticlockwise (a fourth up). C has none, G has one sharp, D has two, and so on. To name a sharp key, the last sharp is the leading note, so the key is a semitone above it. To name a flat key, the second-last flat names the key.

Why this matters for the exam

Dictation, harmonic analysis and composition all assume you can move between a key signature, its scale and the intervals within it instantly. A student who has to derive the pattern each time loses marks to time pressure and small slips. The fix is drilling: write every key signature and scale from memory until they are reflexes, then test recognition by ear.