edit: here's a video on reactable's website of kids interacting with the 'instrument'.
A REACTABLE at barcelona's astounding science museum, cosmo caixa. i probably played with this thing for twenty minutes, as pack after pack of kids came, played, and moved on. i had always thought the reactable was so cool that i was clearly never going to actually see one, let alone play with it. and yet, here it is! i could have stayed for hours just for this. barcelona, nearly home.