All Harpsicle music is in the key of C.  Sets of music vary in difficulty from very easy to not-quite-as-easy and is intended for beginners.  Even experienced players will find that sometimes just a simple little ditty will do for their purposes.  Included in this set are:

Old Folks at Home (Swannee River); Oh Susanna; On Top of Old Smokey; Bingo; The Muffin Man; Mary Had a Little Lamb; Camptown Races; Kookaburra; Michael Row Your Boat Ashore; Sweet Betsy from Pike; Wheels on the Bus; Hot Cross Buns; I'm a Little Tea Pot; This Old Man; Row, Row, Row Your Boat.