"If you mix up bubble bath so it's all foamy, is it a solid, a liquid, or a gas?"
Don't answer too quickly! Think about it. I said, "It's a liquid, because if you poured the foam into a container, it would take on the shape of the container."
But, Supersim pointed out that you mixed it up right, you could scoop up pieces of the foam and they would retain their shape. True.
She also reminded me that all those bubbles would make it a gas. "No," I said, "Gas particles expand to fill the entire room. Those bubbles are trapped in the foam."
"Until they pop!" she said. "Then the gas in them expands to fill the entire room!"
A real live scientist would probably cringe at this conversation, since we're speculating about things that we don't really understand. There is probably a scientific label for "bubble bath-type matter."
But I LOVE that she's thinking about these things! I love it when the kids pose questions that I can't answer, because it's a great opportunity to learn something together. We'll keep you posted on the bubble bath controversy...