Grade Five Music Theory - Lesson 5: Key Signatures

What are key signatures and why do they exist?

Take a look at the mymusictheory.com video on Key Signatures, then read on for a detailed explanation.

In your ABRSM Grade 5 Theory exam, all the musical examples are based on tonal music. Every piece of tonal music is in a certain key, which will be either major or minor.

The key signature tells you what that key is. Key signatures are used in order to make it unnecessary to fill up the staves with flats and sharps on many notes. Also, without a key signature, you would have to do some detective work to find out what key a piece is actually in.

Each key signature represents two keys: one minor key and one major key. Here are some examples, with the keys they represent:

G Major	Bb Major	Eb Major
E Minor	G Minor	C Minor
E Major	B major	Gb Major
C# Minor	G# Minor	Eb minor

How do I write a key signature?

You must write key signatures very carefully. There are two important things to remember about writing them:

• The position on the stave
• The order of the sharps or flats

You will need to know how to write any key signature up to six sharps/flats in any clef for Grade 5 Theory!

The sharps are written in this order: F#, C#, G#, D#, A#, E#.

G major -F#;

D major - F#, C#;

A major - F#, C#, G#;

E major- F#, C#, G#, D#;

B major- F#, C#, G#, D#, A#;

F sharp major- F#, C#, G#, D#, A#, E#

in these positions on the staff (Treble, Bass, Alto then Tenor clef):

The flats are written in this order:

Bb, Eb, Ab, Db, Gb, Cb

F major- Bb;

Bb major- Bb, Eb;

Eb major- Bb, Eb, Ab;

Ab major- Bb, Eb, Ab, Db;

Db major- Bb, Eb, Ab, Db, Gb;

Gb major- Bb, Eb, Ab, Db, Gb, Cb;

in these positions: 

How can I learn all these different key signatures?

1. Position on the Stave 

Learning how to write key signatures correctly isn’t as hard as you might think. 

With the sharp keys, the general "up-down" pattern is the same for treble, bass and alto clef. However, tenor clef is quite different and has to be learnt separately. 

With the flat keys, all the clefs follow the same basic "up-down" pattern. Try to memorise the patterns. 

Look again at the examples above, and notice where the pattern is the same and where it is different.

Make sure you never write a sharp/flat on a ledger line in a key signature!

2. Order of Flats and Sharps 

To remember the order of the sharps, start at F (#) and then count 5 notes forward: F-G-A-B- C. The next sharp is C#. Repeat the process to find the next sharp: C-D-E-F- G, so the next sharp is G#, and so on. 

To remember the order of the flats, starting at B(b) , count 4 notes forward: B-C-D- E, so the next flat is Eb . Repeat the process to find the next flat: E- F- G- A , so the next flat is Ab , and so on.

Remember that you count 5 for sharps- the word “sharp” has 5 letters!

Remember that you count 4 for flats- the word “flat” has 4 letters!

Another method is to learn a phrase like this:

Father - Christmas - Gave - Daddy - An - Empty - Box

The first letter of each word gives you the order of sharps. F-C-G-D-A-E-B. Write the letters backwards to find the order of flats B-E-A-D-G-C-F! (This phrase has seven sharps and flats, but you only need to learn up to six for grade 5 theory!)

How do I work out a major key from a key signature?

Sharps

If you have a sharp key signature, look at the last sharp in the pattern. This is the leading note, which is the 7th note in the scale. The next semitone up will be the tonic, or 1st note in the scale, and will be the major key.

For example, look at the following key signature:

The last sharp in the pattern is G#. The next semitone up is A, so this key signature represents A Major.

Flats

If you have a flat key signature, you’ll first have to remember that F major uses 1 flat (Bb). For all key signatures with 2 or more flats, the last but one flat in the pattern represents the major key.

For example, look at the following key signature:

The last but one flat in the pattern is Db, so this key signature represents Db major.

How do I work out a minor key from a key signature?

The minor key represented by a key signature is always that of the 6th note of the scale in the major key (also called the sub-mediant). For example, in C major, which has no flats or sharps, the 6th note is A:

So, A minor also has no flats or sharps. We say that A minor is the "relative minor" of C major.

Use the same method for flat and sharp key signatures:

A major => F# minor

Ab major => F minor

For an example of how relative major/minor keys can be combined in a real composition, read Eric Strom's post on relative key in the song "Mirrors" by Justin Timberlake.