OK, I'll admit it. Until two years ago, I had never even heard of Boomwhackers. Pitched, colored PVC pipes at a cheap price - how cool is that! They even make little "caps" that slide on the end to make them sound one octave lower if desired. We have several octaves. They come in diatonic sets (key of C ) and chromatic sets.
To play them, students can hit them on the floor, a chair, or hold one in one hand and hit the pipe into the other. There are several videos on Youtube that show their versatility.
We group the pipes into the basic major chords of a simple song (ie. C, F, G etc). By dividing the kids into three groups, lots of kids can participate by chording along with a song - and all they have to do is hit the boomwhacker when I point to their group. Furthermore, since they are pitched, one day I had a crazy idea and passed them out to my adult handbell choir to try them with regular handbell music. That what one crazy rehearsal! Since they are so inexpensive, I'm thinking about getting another set to be able to simultaneously use them with two different groups.