Abstract: An elongated flexible sheet (20) contains numbers (22, 26) and corresponding parallel lines (24) that are aligned with the holes (13) of a harmonica (11). The top portion of the sheet (20) contains rows (30, 37, 40, 47) of respective color-coded blocks (32, 34, 36, 38, 39, 52, 54, 56, 48, 49) superimposed over the parallel lines (24). The color-coded blocks (32, 34, 36, 38, 39, 52, 54, 56, 48, 49) encompass sets of lines (24) that correspond to chords which may be played on the harmonica (11). The colors are chosen to create a mnemonic reference. The sheet (20) attaches to a harmonica (11) and is flexed into a viewing position for ready reference upon grasping the harmonica (11).