Somebody wasn't happy that the Tone Bars weren't out and took it upon himself to set them up.
Next we took out the red glass beads and I asked him to start with the first tone bar (G) and then build a scale using all whole steps. He played it. Then, I asked him to start on the G# and do the same thing. He played it. I asked him to start on the A and do the same thing. He observed that even though we had a different starting point we used the same bars that we did when we built the scale on the A. Then he predicted that this would happen if we used any starting note from the first scale. He quickly realized that although we have 12 potential starting points, there are only two possible sets for the whole tone scale.
It would probably be more consistent with the rest of the Montessori music materials if I were to make green and white scale pattern strips for all of the scales we plan to learn (major, minor(s), chromatic...which would be all white by the way, whole tone, pentatonic, and octatonic). However my boys didn't need them for chromatic and whole tone. Also, I was inventing this lesson on the fly. It is a lot easier to grab glass beads that pull a two-color oversized laminated scale strip out of my hat.
Afterward he built some major scales using the scale strip. It looks like we have E major up there.
To stimulate some more practice building major scales I added an extra point of interest. After building the scale with the strip the boys can mount the scale on the Scale Ladder.