Reference

Relative key

A major and minor key sharing one set of notes and one key signature. Count three half steps down from the major tonic.

relative minor · relative major

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