Reference

Circle of fifths

A diagram arranging all keys by fifths. Clockwise adds sharps, anticlockwise adds flats, and neighbours share six of seven notes.

CAmGEmDBmAF♯mEC♯mBG♯mG♭E♭mD♭B♭mA♭FmE♭CmB♭GmFDmouter ring = major
inner ring = relative minor

Clockwise adds a sharp at a time, anticlockwise adds a flat at a time

Where it's taught