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 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#:
Look at the pattern: it goes down, up, down, in both clefs!
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:
Look at the patterns: up, down, up, in both clefs - the opposite to the sharps' pattern!
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 (make sure you count 3 different letter names too):
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.
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 (sharps and flats next to the notes) 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 raised 7th note.
G minor harmonic (F becomes F#)
C minor harmonic (Bb becomes B natural)
All melodic minor ascending scales have raised 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.
For a complete list of all the major and minor scales, see our List of Musical Scales.