Construct and identify major, minor and modal scales, work out key signatures, and recognise tonality aurally.

What this dot point is asking

Building major and minor scales

Every diatonic scale is a fixed pattern of tones (T, a whole step) and semitones (S, a half step). The major scale pattern is 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. Move the same pattern to G and you must raise the seventh note to keep the final T S, producing F sharp.

The minor scale has three working forms. Natural minor is T S T T S T T, so A natural minor is A B C D E F G A. Harmonic minor raises the seventh degree by a semitone, giving A B C D E F G sharp A, which creates the leading note needed for a strong perfect cadence. Melodic minor raises the sixth and seventh ascending (A B C D E F sharp G sharp A) and reverts to the natural form descending. Knowing which form is in use is a common exam task.

Key signatures and the circle of fifths

Key signatures collect the sharps or flats a key needs so you do not write them on every note. They follow the circle of fifths. Moving up a fifth adds one sharp: C, G (1 sharp), D (2), A (3), E (4), B (5). Moving down a fifth (or up a fourth) adds one flat: C, F (1 flat), B flat (2), E flat (3), A flat (4).

Sharps are added in the order F C G D A E B, and flats in the reverse order B E A D G C F. A quick check for sharp keys: the last sharp is the leading note, so the key is a semitone above it. For flat keys, the second-to-last flat names the major key.

Each major key shares its signature with a relative minor a minor third below. C major and A minor both have no sharps or flats; G major and E minor both have one sharp. To tell them apart you look at which note behaves as the tonic and whether the raised seventh of the minor appears as an accidental.

Modes

Modes are scales built by starting the white-note pattern on different degrees, and they appear often in jazz, folk and film music. The seven modes from C are Ionian (C, identical to major), Dorian (D, a minor scale with a raised sixth), Phrygian (E, minor with a flattened second), Lydian (F, major with a raised fourth), Mixolydian (G, major with a flattened seventh), Aeolian (A, identical to natural minor) and Locrian (B, rarely used). For analysis you describe a mode by comparing it to major or minor and naming the altered degree, for example "Dorian, a minor scale with a raised sixth".

Hearing tonality

Aural identification starts with the tonic chord. Play or sing back to the resting note, then decide whether the tonic triad sounds bright (major) or darker (minor). Listen for the leading note: a clear semitone push to the tonic suggests major or harmonic minor, while a whole-tone step below the tonic suggests a modal or natural-minor colour. A flattened seventh in a major-sounding tune points to Mixolydian; a raised fourth points to Lydian.

Putting it together

In both the written exam and aural tasks you move between three skills: constructing a scale from a pattern, deriving or naming a key signature, and judging tonality by ear. Practise writing each minor form from memory, drilling the circle of fifths in both directions, and singing tonic-to-leading-note to lock the sound of major against minor.