Such a cool story, Susanne! It reminds me of a study done on museum users from a long time ago -- the 1980s I think. Anyway, the research found that there were three kinds of museum patrons, and they classified them as Strollers, Studiers, and Streakers.
I designed some touch screen kiosks for a local cultural centre in Saskatoon in 1986 and 1990 -- yes, using the big 12" optical videodisc technology that was the bleeding edge of technology and the time. I loved working on the project, but enjoyed even more going back to the centre and eavesdropping on kids and parents who used the displays. Hard to believe, but one of those projects is still running today, 22 years later. I think the secret to its success was exactly what you described -- it invited kids to explore, and it didn't present a bunch of static information.