Yesterday, out of the blue, I looked at my kids and said, "do, re, mi, fa, sol, and so on are only the tools we use to build the song. Once you have these notes in your head, you can sing a million different tunes, by mixing them up, like this: so, do, la, fa, mi, do, re. Can you do that?" And my kids did!! Then I sang, "sol, do, la, ti, do, re, do." They sang that too. I told them that I had been waiting for this moment my whole life. They thought I was weird. I don't mind.