# The Great Race

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On our planet, we find water in three states of matter: solid, liquid, and gas. What factors affect how fast water changes from one to the other? Try this experiment to find out!

Age: 4-10
Time: 20 minutes or more
Topics: states of matter, melting, evaporation

What you need:

• Small bowls or cups
• Small plates
• Ice cubes
• Water
• Clock or timer
• Eye dropper or spoon
• Optional: lamp, fan, sunny window

What to do:

1. Think about different ways you could make an ice cube melt. Where have you noticed ice (or other frozen things) melting before? Make a prediction about which of those ways would make an ice cube melt the fastest.

2. Choose three or four different ways or places to test. Try ideas like these (but you can be creative and think of your own, too):

• Outdoors
• Upstairs or downstairs in your home
• Near a lamp
• Near a sunny window
• Near a blowing fan

3. Place an ice cube in a small bowl or cup. Make three or four of these (one for each place you will test). Put each one in a different place at about the same time and record how long it takes to completely melt.

4. Which one melted the fastest? How did that compare to your predictions? Why do you think that happened?

5. Now it's time to test evaporation. Make a prediction about which of the places you tested with the ice cube will make water evaporate the fastest. Will it be the same as melting, or different? What makes you think so?

6. Use an eye dropper or spoon to place a few drops of the melted ice cube water on a plate. Make one plate for each location, being careful to put about the same amount of water on each. (Why do you think that’s important?)

7. Put those plates of water into the same places where you put the ice cubes. Time how long it takes for the water to evaporate. (Be prepared, this could take a long time.)

8. Which one evaporated the fastest? How did that compare to the place where the ice cube melted the fastest? Why do you think that?

9. Other ideas to try:

• Repeat the experiment two or three different times. Do you get the same results each time? If not, what do you think might explain the differences?
• Choose new places to test and try the experiment again. How do these places compare to your first ones?
• Make a chart that shows the places from fastest melting (or evaporating) to slowest.
• What else affects how fast an ice cube melts? Does the shape or size of the container matter, or whether it is covered or uncovered, or the time of day when you start? Design an experiment to test your idea!

What’s happening?

Materials can change from solid to liquid, and from liquid to gas, because of heat energy. As an ice cube absorbs heat from its surroundings, the molecules of water get more energy. They begin to move more fluidly as the cube melts into a liquid. Liquid water also absorbs heat from its environment, making the molecules gain even more energy. They spread apart and move faster, and eventually the water evaporates into the air as water vapor.