Saturday, April 16, 2011

density, part 2

We played around with density again during this week's Science Fridays meeting. First we reviewed the experiment we did last week, and discussed again why the hot water floated on top of the cold water. (Because when you heat water, the molecules move further apart, making it less dense.)

Then we experimented a bit with popcorn:

Why does an unpopped popcorn kernel sink, yet a popped one floats? The unpopped kernel is more dense.

Our little molecules, all bundled up together inside of a popcorn kernel.

We add bit of heat and...

POP! The molecules move away from each other, and the popcorn kernel explodes outwards.

We also floated bits of bread in water. Then we made the bread bits more dense by squishing them into balls, which then sank.

Back to the popcorn....we popped a bunch of popcorn, and the kids pretended they were molecules in a substance, making the substance more and less dense by piling the popcorn together in the center of their plate and by spreading it out around their plate.

Then we let them make their substance really dense, by adding a bit of melted marshmallow and butter and really pushing those popcorn "molecules" together....squish, squish....

Result = one dense popcorn ball. (Yum!) And 140 really sticky fingers....

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