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    Molecules and density- beginner's style!
    By Molecules and density- beginne

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    I actually give my kids a pretty scientific explanation for this and they seem to understand. We first talk about how everything is made up of molecules; sometimes the molecules are spread apart and sometimes they are close together. If the molecules are close together, there is less air between them. We demonstrate this by having a small group of children stand in a circle holding hands. I ask them how close they can get (dense molecules) and how far apart, without letting go of their hands. When something sinks, it becomes waterlogged as the spaces fill up with water, making the item heavy. (There is also a water displacement factor, but that gets REALLY technical!)THink of a sponge, very light and filled with lots of air pockets. As it becomes waterlogged, the pockets fill with water, it becomes heavier, and it sinks. Matter that has dense molecules does not have as many air pockets, and so it takes longer for it to become waterlogged. We do an experiment in which we use paper clips attached with a rubber band to see how long it takes various items to sink. The class is so surprised that the heavier items don't always sink first! I hope that makes sense, my kids seemed to understand!

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