The Complete Idiot''s Guide to Music Theory

46 Par t 1:Tones

Using Key Signatures

One of the convenient things about assigning a particular key to a piece of

music is that it enables you to designate the appropriate sharps and flats up

front, without having to repeat them every time they occur in the music.

Here’s how it works.

You designate a key by inserting a key signatureat the very start of the music,

next to the first clef on the first staff. This key signature indicates the sharps

and flats used in that particular key. Then, when you play through the entire

piece, you automatically sharpen and flatten the appropriate notes.

For example, let’s say you write a song around the F Major scale. The F Major

scale, if you recall, has one flatted note: B-flat. So next to the first clef on the

first staff, you put a flat sign on the B line. Now, when you play that song,

every time you see a B, you actually play B-flat.

The key signature for the key of F—note the flat sign on the B line, indicating the automatic

B-flat.

The same would apply if you were playing in the key of G, which has one sharp:

F-sharp. You put a sharp sign on the top F line on the first staff; then every

time you see an F, you play an F-sharp.

Major Keys

Just as there are 15 major scales (including three enharmonics), there are 15

major keys; each with its own key signature. The following table shows what

each key of these key signatures looks like, along with its corresponding scale.

The 15 Major Keys

Key Key Signature and Scale

C Major

C-sharp Major

D-flat Major