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.
A key signature is a contract: these notes are altered unless I say otherwise.
A key signature says “every F is sharp” or “every B is flat” without writing the accidental before each note. This lesson shows where every key sits in relation to every other.
The circle
Up a perfect fifth 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.
The same shape in C, G, and F — only the home pitch moves.