A child's view of foam

"Are you a grown-up?" I looked up, or more precisely down, into the eyes of a child. He had good reason to ask this since I was playing with bubbles at an exhibition for very young scientists. What attracts them? What does not? Physicists have been arguing over whether or not to consider it a duty to encourage children to enter physics. I would like to describe the actual experience of standing among the young and curious.