A classroom version of Willoughby Wallaby Woo that includes short solos for each child.
Notation for Willoughby Wallaby Woo is freely available on Raffi's website, with chords for guitar in G. To simplify for the ukulele and lower the pitch slightly, substitute the chords F, G7 (or G), and C (change all G chords to F, all A chords to G7 or G, and all D chords to C).
One recording of Saint-Saëns' The Elephant, played on piano and bass.