In this video, we will recap using the Rectangle of Fifths to intuitively recognise the Key Signature of Flat Major Keys with their Tonic on a black note.

When the tonic of a major key moves from a white key to a flat (♭) position, the sharp (♯) positions move to white keys, and the white keys move to flat (♭) positions.

Rule for Identifying Flat (♭) Key Signatures:

Subtract the corresponding white tonic keyboard position value from seven.