This short and very easy song is actually a guitar feature that lets players sing and whistle as well. Have students sing or whistle and play at the same time, or split your class so that some sing or whistle while others play guitar.
The simple guitar line includes three 4-string chords: D, G, and A7. The suggested strumming rhythm is indicated on the music, but you can alter it any way you like to make it harder or simpler. The kit includes an extracted guitar part if you want your students to read the rhythms. (from Music K-8, Vol. 27, No. 3)