Shhh! Don't bounce the balls

I'm telling y'all whoever came up with this idea is a genius... If you go to this website and turn on your microphone this screen will pop up:

 I have found it worked best with upper grades (3-5)...

When the microphone picks up noise the balls will bounce. Whenever it is quite they will be still. I tell my kids they have to keep the balls still and cannot make them bounce. They work so quietly because they are scared the balls will go bouncy crazy.

Here is the website: http://bouncyballs.org