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When does water float?

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This first experiment deals with the density of water in both its liquid and solid state. You may want to give your child a little bit of background on density: essentially that density is how tightly together molecules are packed, and that a denser object will sink.

Materials needed: * Water * Cooking oil * Clear plastic container (like an empty soda bottle with the label removed) * Food coloring * Freezer

Procedures Hypothesize - What will happen when this water and oil are poured into the same container?

Add a few drops of food coloring to the water.

Pour the water into the clear plastic container.

Pour in the oil.

Observe and conclude - What happened? Was the hypothesis correct?

Place the container in the freezer. What do you think will happen?

After a couple of hours remove the container and observe.

What does this mean about the density of water? Unlike most liquids, as water freezes it actually expands and becomes less dense than oil. This causes the water/ice to rise to the top. Now try to connect this learning to what it means about the world around us. Think about what happens to a pond in the winter. What would happen to the pond if water performed like most liquids and sank when it changed to a solid? You can assess if your children understand what this means by simply having them hypothesize what will happen if they drop an ice cube in a glass of water.

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