Lesson 21: Key Signatures and the Circle of Fifths
- Name the changed notes in five common key signatures.
- Keep the key’s sharps or flats in a melody.
Read the signature before the notes.
The key signature beside the clef changes named notes in every octave. A natural sign cancels that change through the bar.
The circle
Count five letter names up from C — C → G → D → A → E — each step adds one sharp; down a fifth — C → F → Bb → Eb — each step adds one flat.
- C major / A minor
- No sharps or flats.
- G major / E minor
- One sharp: F#.
- D major / B minor
- Two sharps: F#, C#.
- F major / D minor
- One flat: Bb.
- Bb major / G minor
- Two flats: Bb, Eb.
Play the same rhythm in C, G, and F.
Play the same rhythm in F, C, and Bb.
Play: Au clair de la lune — read the signature
One sharp makes every F sharp; watch its third phrase.
Your staff reads C major; keep B natural in the third phrase.
Widor, Vieilles chansons, p. 6; melody only, public domain.
Now play these
- Bingo
- G major: one sharp, F-sharp.
- C major: no sharps or flats; keep B natural.
- Pavane: Belle qui tiens ma vie
- G Dorian: one flat, B-flat, with cadential F-sharps.
- C Dorian: two flats, B-flat and E-flat, with cadential B-naturals.
When you can name the five signatures and play Au clair de la lune without losing its changed note, continue to Lesson 22.