This one is lots of fun to do with young children; it’s nice and easy for guitar, ukulele or banjo, and you can play at a nice, relaxed pace until you’re confident with the chord changes.

…

Here are the links to the song sheets:

….

for guitar - gL 4_This Old Man _G,D7,C

….

for ukulele - uL 2_This Old Man _G,D7,C

….

for banjo - bL 3_This Old Man _G,D7,C