Lesson 21: Key Signatures and the Circle of Fifths
- Read a key signature without thinking about it.
- Name the sharps or flats in any common key.
- Lessons 11 and 14 — sharp and flat keysigs in practice.
- Key signatures.
- Circle of fifths.
- Key relationships.
A key signature is a contract: these notes are altered unless I say otherwise.
A key signature sits between the clef and the time signature; it says “every F is sharp” or “every B is flat” without writing the accidental in front of each note. You have been reading them for ten lessons already. This lesson gives them their formal name and shows where every key sits in relation to every other.
The circle
Move up by a perfect fifth from C: C → G → D → A → E. Each step adds one sharp. Move down by a fifth: C → F → Bb → Eb. Each step adds one flat. C major sits at the top with zero accidentals; the keys spread outward in both directions.
- C major / A minor
- No sharps or flats.
- G major / E minor
- One sharp: F#.
- D major / B minor
- Two sharps: F#, C#.
- A major / F# minor
- Three sharps: F#, C#, G#.
- F major / D minor
- One flat: Bb.
- Bb major / G minor
- Two flats: Bb, Eb.
- Eb major / C minor
- Three flats: Bb, Eb, Ab.
A short melodic shape in C, G, and F. Listen for the same intervals each time; only the home pitch moves.
Now play these
One piece in each of three keys, to fix the habit of reading the key signature first.
- Ode to Joy · C major
- No accidentals. The home key.
- Scarborough Fair · G major
- One sharp. Watch every F.
- Pavane: Belle qui tiens ma vie · F major
- One flat. Watch every B.
When you can name the sharps or flats of C, G, D, F, and Bb major from memory without pausing, move on to Lesson 22.