Abstract: Slide-rule type devices for music study. Requires two printed parts that slide relative to each other; or three parts in the special case of a device for studying violin. Information on one of the parts is viewed through the other part. When employed together, the two parts reveal information most relevant in a particular musical scale or key, and obscure the information not normally used in that key. Multiple embodiments are possible, allowing a device to be constructed specific to a given instrument such as a violin or guitar, but the concept is not limited to stringed instruments, or any instrument. Similar devices could be made to facilitate music study for voice students, songwriters and arrangers. One of the sliding pieces is printed with all the available notes or tones, say, in the range of an instrument like a guitar. In the most likely embodiment, the other piece contains a transparent window printed with a series of geometric shapes of varying colors.