Grade Three Music Theory - Lesson 4: Key Signatures
Key signatures have to be written very carefully. You need to make sure the flats and sharps are written
- in the right order
- in the right position
In the grade three music theory exam, you need to be able to write and understand key signatures with up to 4 sharps or 4 flats.
Sharp Key Signatures
The sharps, in order, are F# - C# - G# - D#.
F# is used for G major and E minor
F# and C# are used for D major and B minor
F#, C# and G# are used for A major and F# minor
F#, C#, G# and D# are used for E major and C# minor
Position of the Sharps
In the treble clef, F# is always written on the top line:
In the bass clef, it’s always written on the second line from the top:
C# is written lower than the F#:
G# is written higher than C#:
D# is written lower than G#:
Flat Key Signatures
Position of the Flats
In the treble clef, Bb is written on the middle line:
In the bass clef, it’s written on the 2nd line from the bottom:
Eb is written higher than Bb:
Ab is written lower than Eb:
Db is written higher than Ab:
Relative Major and Relative Minor
We say that G major is the “relative major” to E minor, and that E minor is the “relative minor” to G major, because they use the same key signature.
To find out what the key signature is for a minor key, you first need to find the key signature for its relative major. So if you want to find the key signature for C# minor, you need to work out what the relative major of C# minor is.
To find a relative major, count upwards one tone and one semitone:
C# - D# is one tone,
D# - E is one semitone.
Therefore, the relative major of C# minor is E major. It has 4 sharps.
To find out the relative minor, do the opposite – count downwards one semitone and one tone:
G- F is one tone,
F - E is one semitone.
So, the relative minor of G major is E minor.
Key Signatures and Minor Keys
The key signature for a minor key includes all the sharp/flat notes from the natural minor scale – this is the same as the descending melodic scale.
For example, A minor melodic descending is A-G-F-E-D-C-B-A. There are no sharps and flats, so there are also no sharps or flats in the key signature for A minor.
Some students think that because A minor harmonic includes G#, there must be a G# in the key signature. This is a mistake.
When you write a minor scale with a key signature, you will need to add some accidentals if the scale is
- harmonic minor, ascending or descending
- melodic minor ascending only
Don’t forget that you also sometimes need to add naturals, to cancel flats from the key signature.
Here are some examples of minor scales with a key signature and accidentals:
All harmonic minor scales have a sharpened 7th note.
G minor harmonic (F becomes F#)
C minor harmonic (Bb becomes B natural)
All melodic minor ascending scales have a sharpened 6th and 7th notes:
C# minor melodic (A and B become A# and B#)
F minor melodic (Db and Eb become D natural and E natural).
A quick way to check which key a key signature represents:
- in sharp key signatures, the last sharp in the key signature is the leading note. It’s one semitone lower than the tonic of the major key. For example:
The last sharp is D#. The note one semitone higher than D# is E. This is the key signature for E major.
- in flat keys, the last but one flat in the key signature is the tonic of the major key. For -example:
The last but one flat is Ab. This is the key signature for Ab major.