From Plank Road Publishing
In this song the idea is to start with one melodic or percussive line and add to it, one line at a time to a given point. Then, remove the lines one at a time till the ending. We started with rhythm, then body percussion, and then added our highly exaggerated 1950s-style nasal singing layers.
This is an excellent tool for learning rhythms and part singing, and for keeping track of the form of a tune. Our suggested form is printed at the bottom of the music, but you can adapt it anyway you like. (from Music K-8, Vol. 11, No. 5)