Problem:

What is the water cycle?

Research:

Every human, plant, and animal depends on water for survival. It's controlled by the sun, which produces energy in the form of heat. This heat energy causes the water in the world's oceans, lakes, and even puddles in your backyard to warm and evaporate. When water is heated, it changes from a liquid to a gas. This gas is called water vapor, and the process is called evaporation. When plants give off water vapor, it's called transpiration. When water evaporates, it rises into the cooler air, collects, and forms clouds. There, the water vapor molecules cool down and change back into liquid water. This is called condensation. As more and more water vapor cools into the clouds, the water droplets that form the clouds become larger and larger. These droplets get so big that the swirling winds in the atmosphere can no longer hold them up. The droplets fall from the sky. Precipitation is the term for the falling, condensed water molecules, which come down as rain, snow, sleet, or hail--depending on conditions in the atmosphere.

Hypothesis:

We think that water cycle is the way the Earth uses and recycles water.

Material:

1. A large, clear bowl
2. Plastic Wrap
3. A weight
4. A smaller container (example: cut-down yogurt cup)
5. A rubber band or piece of string

Procedure:

Place the small container in the middle of the large, clear bowl. Fill the bowl with a little water, being careful not to fill the small container inside. Cover the bowl with plastic wrap, and fasten the plastic wrap around the rim of the bowl with your rubber band or string. Put a weight on top of the plastic wrap in the center. (See Picture below.) Now put your contraption on a windowsill or somewhere that the sun will hit it.
How long does it take for water to evaporate and condense on the plastic wrap? Where does the water go after it condenses on the plastic wrap?

Record And Analyze Data:

The heat of the sun evaporated the water, which raised, condensed on the cool plastic, and fell into the small container. This is a small-scale replica of the water cycle that occurs every day on earth.