The Old MacDonald Piano app from Kiboomu is a fantastic introduction to music with a well-known kids song, Old MacDonald. Although it is definitely styled for the younger child, anyone beginning music can get a quick start using this app. Personally, I am just starting to learn piano, and I liked practicing the notes and hearing myself on playback. This would be an amazing app with a few more songs and in-app help on how to use the app.
Play and Sing
Learn the Song
Try sounds from different instruments, including piano, guitar and pig!