Lesson Seven: Key Signatures
A key signature is the number of sharps (#'s) or flats (b's) on each staff just after the clef. They tell us which notes to change for each scale to sound major. A key signature is found after the clef sign at the beginning of every line of music.
Key signatures belong to scales. They tell us which scale the notes of the music are from. We already know that scales that begin on different notes have some notes changed in them so they will all sound like major scales. The key signature is the sign for which notes should be changed and tells us which scale this tune is written for.
For our lesson on transposition, we changed the song Twinkle Twinkle from C major to G major. We had to change the notes so that the C major version had only the notes from the C major scale and the G major version had only the notes from the G major scale.
When we changed Twinkle Twinkle to the F major scale notes, we had to use a Bb rather than a B natural because we could only use the notes of the F major scale. The F major scale needs a Bb to make it sound the same as all the other major scales.
The key signature is a short hand way of telling us which scale the notes in the tune are from. If they are only from the F major scale the note that has changed (the Bb) will be the key signature and be put at the front of every stave.
If the tune uses only notes from the G major scale, then the note that has changed (the F#) is put at the front of each staff. This way we can tell right away which notes should be in the tune.
We know that when using the C major scale there are no sharps or flats. What do you think will be the key signature for tunes written in the C major scale? ______________________________
The word KEY is another word for what scale the notes are from. The word SIGNATURE means a sign for. So when we see a KEY SIGNATURE in our music it means that the music is telling us which notes should be in that part.
Sometimes the composer will want to use a note or two that doesn't belong to the key/scale. These are called ACCIDENTALS and they must be marked properly in the music. For instance, if the composer is using a G major key (with an F# at the beginning of every staff) and they decide they want to use an F natural instead, they have to mark it by putting a NATURAL sign in brackets just before that F note.
A NATURAL sign looks a bit like a sharp sign and means that the white notes is used rather than the black note. The key signature sets the rules for what notes should or should not appear in the music and if the composer breaks those rules they have to put the correct sign (the natural sign), to show they are breaking the rules.