Teaching aid especially for music theory has different size concentric discs printed with scale and other information and linked by a central pivot

摘要

A teaching aid especially for music theory has a first disc (1) printed on both sides and fitted with smaller printed discs (2, 3) on each side connected via a central pin. The discs are rotated to provide diatonic scales and other information and are made simply of stiff card with a plastic laminated cover.