The F major scale starts and ends on the note F and contains a B flat (Bb) note. The next example shows two octaves of the F major scale. In the F major scale, a Bb note must be used instead of a B note in order to keep the correct pattern of tones and semitones for the major scale.
Music that makes use of notes from the F major scale is said to be in the key of F major and will likely contain the note Bb. Shown here is the key signature for the key of F major.
The F major scale contains one flat, Bb, therefore the key signature for the key of F major contains one flat, Bb. The following melody is written in the key of F major. Remember to play all B notes as Bb, as indicated by the key signature. Practice it slowly at first and be sure to use alternate picking with all eighth notes.