the identification and construction of major and minor key signatures, the order of sharps and flats, the circle of fifths, and the use of relative and parallel keys in performed and studied repertoire

What this dot point is asking

Key signatures are the shorthand that tells you what key a piece is in. In the aural and written examination you must name a key from its signature, write the correct signature for a given key, and recognise the relationships between keys that composers use when they change key. The circle of fifths is the single diagram that ties all of this together.

The order of sharps and flats

Sharps and flats are never added randomly. They appear in a fixed order.

A common memory aid for sharps is the phrase Father Charles Goes Down And Ends Battle, and for flats the same words reversed, Battle Ends And Down Goes Charles' Father. Each successive key in the sharp direction adds the next sharp; each successive key in the flat direction adds the next flat.

Naming a major key from its signature

There are quick rules. For sharp keys, the last sharp is the leading note, so the tonic is one semitone above it: a signature ending in F sharp means the key is G major (F sharp is the leading note, G is the tonic). For flat keys, the second-to-last flat names the key: with B flat and E flat, the key is B flat major. The single exception worth memorising is F major, which has one flat (B flat).

The circle of fifths

The circle of fifths places C major at the top with no sharps or flats. Moving clockwise, each step up a perfect fifth adds one sharp: G, D, A, E, B. Moving anticlockwise, each step down a fifth adds one flat: F, B flat, E flat, A flat, D flat. At the bottom the sharp and flat keys meet as enharmonic equivalents, for example F sharp major and G flat major.

Relative and parallel keys

Two relationships matter constantly. Relative keys share the same key signature but have different tonics: every major key has a relative minor a minor third below it, so C major and A minor both have no sharps or flats. Parallel keys share the same tonic but different signatures: C major and C minor start on the same note but C minor has three flats. Spotting whether a passage in minor is the relative or the parallel of a nearby major key is a frequent analysis and aural task.

Telling major from minor

A key signature alone does not tell you whether the piece is major or its relative minor, because they share the signature. You decide from the music: look at the opening and closing notes and chords, and listen for the raised seventh (the leading note) that minor keys borrow through the harmonic minor. If the tune keeps returning to and ending on the relative minor tonic, and you hear a raised seventh, it is in the minor key.

Drill the order of sharps and flats until you can write any signature instantly, sketch the circle of fifths from memory, and practise naming both the major and relative minor for every signature. Secure key knowledge speeds up transcription, harmonic analysis and recognising modulations in studied works.