We put a small bit of water in the can. As it boiled it turned the water into a gas state which pushed out the air in the can. When the can was turned upside down in the cold water the gas quickly cooled and condensed back to a liquid pulling in the metal as it did so. A cool experiment!
We also looked again at how when atoms are heated they 'shake' more violently. We were able to see this in action when we dropped some food colouring into both cold water and hot water. The food colouring spread more quickly through the hot water as the atoms were more active.
So we have seen that heat affects density, but we also looked today at how different things have different densities just because of the way they are structured. We looked at how salt water is more dense than fresh water. This gave us lots to think about in terms of things like boats, swimming, survival in deep water, and free diving. Could you dive deeper in fresh water as it is less dense that salt water?
I showed them this photo of me in the dead sea in Israel to help explain differences in water density because of salt content.
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