Questions: Key Signatures and the Circle of Fifths

Question 1

A key signature with three flats indicates which major key?

• A. F major
• B. Bb major
• C. Eb major
• D. Ab major

Answer: (C)

The three flats are Bb, Eb, and Ab (the first three in the order B-E-A-D-G-C-F). To find the major key from a flat signature, the second-to-last flat names the key — here, Eb. Alternatively: one flat = F, two flats = Bb, three flats = Eb, four flats = Ab. This pattern follows the circle of fifths moving counterclockwise.

Question 2

A piece written with no sharps or flats in the key signature has no tonal center — it is atonal.

• T. True
• F. False

Answer: False

No accidentals in the key signature indicates C major or its relative minor, A minor — both have clear tonal centers. A key signature with no sharps or flats simply means the piece uses the natural notes (the white keys on the piano). Atonality is a distinct compositional system that has nothing to do with whether a key signature is empty.

Question 3

Explain why the sharps in key signatures always appear in the specific order F-C-G-D-A-E-B rather than in some other sequence.

Model answer: Each new sharp is a perfect fifth above the previous one (F to C, C to G, G to D, etc.). The circle of fifths organizes all 12 keys by this interval, and adding a sharp always means introducing the leading tone (seventh scale degree) of the new key. The fixed order ensures that each key signature unambiguously identifies exactly one key.

The order is not arbitrary — it reflects the structure of the circle of fifths. When you move clockwise around the circle (adding one sharp at a time), the new sharp is always the seventh degree of the new key, which is a half step below the tonic. Knowing this relationship lets you derive the order from first principles rather than memorizing it in isolation.