Everything Kids' Magical Science Experiments Book by Tim Robinson Page B

counter and mark the height of the water. There should be a small amount of air between the surface of the water and the cap.
Place the bottle upright in the freezer and let it sit for at least three hours.
Take the bottle out of the freezer and notice how the water height has changed.
The Science Behind the Magic
    This seems to be a magical result, but it's not. Water is an unusual substance in that as it freezes, instead of shrinking, as you might expect it to do, it actually expands. This is because of the air that is stored in the water as a liquid. That air expands as the water freezes into ice, and that makes the ice take up more room than the water did. Your bottle may have been distorted slightly, as the ice caused the bottle to expand.
    EXPANSION JOINT: A crack or gap intentionally placed in objects like sidewalks and roads that allow the material to expand and shrink in different temperatures without causing the road or sidewalk to buckle.
    One consequence of this process is that the same amount of water (H2O) takes up more space. The term that describes this relationship between amount of material and amount of space it takes up is density . The more material there is in the same space, the more dense the material is. On the other hand, if you have the same amount of something, but it takes up more space, it is less dense. When the water freezes and expands to form ice, the same amount of material takes up more space and therefore, it is less dense.
    This change explains how ice cubes can float in a glass of water. Since ice is less dense than water, it floats. This is similar to how icebergs, which are really just huge, floating chunks of ice, can float in the ocean.
Follow-Up
    What do you think would happen if you heated up that bottle of water? You have to be careful, because if you heat it too much, the plastic bottle might melt. But here is another place you can see this result. If you have a thermometer at home, the kind you take your temperature with when you are not feeling well, you may be able to explore this. It needs to be the kind that is made of glass, with a thin line of red liquid showing the temperature. When you stick the thermometer in your mouth, the red liquid in the base of the thermometer expands and climbs up the tube until it stops at the temperature of your mouth.
    Can you think of any other examples of liquids expanding or shrinking when you heat or cool them? What about objects that are solid? See if you can find five examples of objects that shrink or expand when heated or cooled.
    Science Online
    This site explores the world of icebergs, and takes a look at the collision that caused the Titanic to sink in 1912: http://oceanworld.tamu.edu/students/iceberg.
    Did You Know?

    Salt is often used on roads and sidewalks as a de-icer. What it does is lower the freezing temperature of the ice. This means that ice made from pure water that has frozen at 32° Fahrenheit may turn to water at that same temperature when mixed with salt.

Try This:Hanging by a Thread
    Ice can be slippery. In the winter, when it snows, the roads often turn icy and people have a hard time driving on it. If you have ever tried to ice skate, chances are, the first time you tried it you found out just how slick ice can be. Even picking up ice cubes can be difficult, as they tend to slip right out of your hands. So perhaps there is a better way—don't use your hands!
    Question: Can you lift an ice cube without touching it?
Materials
Several large ice cubes, taken directly from the freezer
Salt
String that can be cut into pieces
Scissors
Paper towel
Procedure
Place one ice cube on the paper towel.
Cut a piece of string at least 12 inches long.
Without touching the ice cube with your hands, try to lift the ice cube using only the string.
Lay the string across the top of the ice cube, leaving several inches free on either side.
Pour salt on the ice cube, covering the top of the ice and the string.
Wait 3–5