This is a wonderful music and science activity, and I really like it that you have this set up as a child-choice activity, not as something that requires constant supervision. I’m prepared to bet that no child has ever broken a bottle, let alone got cut. Give children responsibility and they rise to it.

I’m going to have to correct you on your explanation of the reason for the change in pitch, however; it’s not to do with how much air is in the bottle.

The real reason is that adding water increases the total mass (weight) of the bottle. Objects with greater mass vibrate more slowly than objects with less mass, and slower vibrations equal lower pitch. See the section labelled “Liquid Volume” on this page http://www.philtulga.com/HomemadeMusic.html.

I’m not being picky, I’m just sure that you would want your thousands of readers to know the correct physics of this wonderful instrument.

::: Thank you so much for the physics lesson Alec, we really do appreciate it … It’s a good thing for us we work with 5 year olds as opposed to 25 year olds! Hee … hee … hee!

In regard to the children handling glass bottles. We have used glass for YEARS in all sorts of different play situations. In all that time we have had 1 pottery utensil pot broken … by an adult!!!

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