This very basic blending of 4/4 meter with 3/4 meter is meant to introduce or reinforce the concept of switching meters in a song. It literally goes back and forth from one measure to the next, so kids have to pay attention.
This song is a partner song, so each of the two melodies occurs separately at first, and then both are combined. Part 1 emphasizes the meter switch by counting the beats. Part 2 names the two meters that are switching and explains that this is what mixed meter is. Simple, but effective.
The kit includes recordings in slower and faster tempos. (from Music K-8, Vol. 24, No. 5)