Abstract: A device for demonstrating musical scales and chords in various tonics for use with a fretted stringed musical instrument. A housing is of a slide-rule nature and has a transparent simulated fingerboard positioned within a display window. This fingerboard is reticulated, with an imprinted series of uniformly-spaced parallel string lines extending longitudinally and representing the strings of the instrument. These lines are regularly interrupted by an imprinted series of position alignment indicia and tone letters. A series of uniformly-spaced printed parallel lines transverse the longitudinal lines and represent the nut and frets of the instrument. Additional display windows disclose a plurality of related information; these windows are used primarily to identify certain tonal characteristics. A plurality of displaceable medial sliding members is provided, each having a system of tone indicators printed in a predetermined manner. These indicators are used to identify tonality.