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The Water Cycle at Work
 The ocean helps drive the water cycle on Earth. The water cycle explains how water moves from the ocean (and the land), into the sky and then back down again. Try this activity to build a model of the water cycle.
What You Need
• Salt
• 1 large clear plastic tote
• 1 plastic drinking cup
• Clean marbles
• Clear plastic wrap
• Masking tape
What to Do
1. Make salt water by adding 30mL (2 tablespoons) of salt to 1L (4 cups) of water. (Repeat if you need more water.)
2. Place the plastic cup in the middle of the tote. Add some marbles so it stays in one place.
3. Add your salt water to the tote. It should cover the bottom of the tote to a depth of about 5cm (2
inches).
4. Have an adult help you cover the top of the tote in plastic wrap. Use tape to secure the plastic tightly.
5. Put a rock or marble on the plastic wrap, directly above the cup.
6. Place your plastic tote in the Sun. (It can be outside or in a sunny window.)
7. Observe what is happening in your water maker several times during the day.
8. At the end of the day, remove the plastic wrap and see if there is any water in your drinking cup. Taste it. Is it fresh water or salty water?
How it Works
The salt water in your model is like the ocean. Water evaporates in the Sun. This means it changes from a liquid to a gas (water vapour). The water vapour condenses on the plastic wrap. This means it changes back into a liquid. This water — which is fresh, not salty — drips into the glass. When water evaporates, the salt is left behind. Your model works just like the water cycle in nature.
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