Abstract: The apparatus includes a base associated with a rotatable display disc representing notes of a musical keyboard, such notes being separated by spaced intervals in proportion to the musical intervals of pitch between the indicated notes. The base has a longitudinally moveable section which may be brought into registry with another indicia to provide visualization of the interrelationship between musical notes. The apparatus may include a keyboard as the longitudinally moveable section, and indicia relative to the longitudinally moveable section may indicate chords relative to a base note.