I first found this song in my "Spotlight on Music" Curriculum and my students in 4th grade loved it. They are in 7th grade now and still ask to sing it all the time.
Over time I moved this song into my 1st grade curriculum as a way to practice singing with expression (dynamics in particular), solo singing, and form. I also use this song in spoken form and have students create sound effects to accompany the lyrics.
The melody of this song is fairly complex but I've been able to sing the song fairly well with my younger students on Sol Mi and La. If you have the Spotlight on Music curriculum CD's this can be easily used as a visual accompaniment to the recording.