Activity 1: Water Cycle

Explain to the students that water changes from one form into another naturally in the environment. Choose one of the two water cycle activities to help students understand how water changes from one form into another in nature.

1. Water Cycle in a Cup:
   1. Organize students into groups of two and explain the directions for the Water Cycle in a Cup activity. Review key vocabulary that are labeled on the Water Cycle Diagram and make sure students understand their meaning.
   2. Color the Landform Cutout.
   3. Tape the landform drawing to the back of the cup.
   4. Add 60 ml (1/4 cup) of water to the earth cup and cover with plastic to keep the water from evaporating.
   5. Use a crayon or permanent marker to mark the starting water level with the current time.
   6. Place the cup outside in the sun for 1/2 hour.
   7. Observe and discuss changes.
2. Water Cycle Demonstration:
   1. Take the clear, large plastic bowl and place the smaller container (butter tub) in the middle of the large bowl. Pour water into the large bowl, around the small container, but not inside the small container. Fill the large bowl until the water level reaches to about three-fourths of the height of the small container.
   2. Place a piece of clear plastic wrap over the large bowl. Put the rubber band around the top of the bowl to keep the plastic wrap in place. Take the weight (rock) and put it in the middle of the plastic wrap. Place the “water cycle” inside the classroom in a sunny spot (like a windowsill).
   3. The sun will heat the water in the large bowl so the water will evaporate, just like the water did in Activity 1. Here the liquid form of water has changed into gas. The evaporated water (gas) will rise and condense on the plastic wrap. This means that the water vapor has turned back into liquid. The water droplets will slide down the plastic wrap until they are underneath the weight (rock). Then they will fall into the small container. The small container collects the water that has been “recycled.”

Activity 2: The Earth’s Water Supply

1. Discuss the Earth’s water supply using the information from the introduction.
2. Display the following information on a poster or the chalkboard.
3. To demonstrate how much of the Earth’s water supply is actually used, ask some students to help you with the next steps. (Make sure that the students understand this is just a demonstration and there is actually more water than this on earth.)
4. Pour water into a one-gallon container, such as a plastic ice cream bucket. This represents all the water on the earth.
5. Pour a half-cup of water out of the one-gallon container and into a clear bowl. The water in the bowl represents all of the fresh water on earth, which is less than three percent of the total water on earth. Fresh water is found in lakes, rivers, groundwater, ice, and living things. The 15 half-cups that are still in the one-gallon container represent salt water. We cannot use salt water without first removing the salt in a process known as desalination. Though research and technology are improving this process, it is still prohibitively expensive and often impractical.
6. With an eyedropper, drop one drop of water from the half-cup onto a small plate. This one drop represents the freshwater that is available for our use. This water is found in rivers and lakes. The rest of the water in the half-cup is deep groundwater, water bound up as soil moisture, biomass water, or water in the atmosphere.