The key signature is the group of sharps or flats at the start of every line of music. It tells you which notes are sharp or flat throughout the piece. It is simple to understand, and surprisingly easy to forget in the middle of playing.
What the key signature does
If the key signature has one sharp on the F line, every F in the piece is played as F sharp, in every octave, until the key signature changes. Two flats on B and E mean every B is B flat and every E is E flat. This saves the composer from writing the same sign again and again.
Why it is easy to forget
The problem is that the information is far from the note. The sign is at the start of the line, but the note you are playing may be at the end of it. With five or six sharps or flats, you have to hold all of them in your head while you read, and one forgotten flat is enough for a wrong note.
Two classic tricks
- Sharp keys: the last sharp in the key signature is one step below the name of the major key. One sharp, F sharp, means G major.
- Flat keys: the second-to-last flat is the name of the major key. Two flats, B flat and E flat, means B flat major.
These tricks help you name the key. They do not help you remember, in bar 23, that the A is actually A flat.
In iCanPiano Style the key signature is only a label
In iCanPiano Style the key signature is still there, at the start of the piece, so you know the key. But every note on a black key already shows it, so you never need the key signature to work out a note.
- F sharp: right half black. Play the black key to the right of F.
- B flat: left half black. Play the black key to the left of B.
- B natural: no natural sign. A note that is all black or all white is played on a white key.
Keys with many sharps or flats, which scare many players away from beautiful music, read just as easily as C major.