Wasting Water – Session 1
Conduct this session in the classroom.
- Set up a demonstration area in the classroom with water containers (see Materials), salt, an eyedropper, and a globe (if there is no world map displayed in the room). Fill one container with a liter of water. Write "1 liter = 1000 ml" on the board. With each subsequent step, write the measurements on the board—in the form of a mathematical statement, when appropriate. You may choose to ask students to assist in this demonstration.
- Before proceeding with the demonstration, place a bucket underneath a dripping faucet, and note the time. Allow the faucet to leak until the end of Session 1; the results will be used in Session 2. (If a faucet is not available you can suspend a gallon jug over the bucket. Prick the bottom of the jug with a pin or small nail to allow drops to escape.)
- Tell students that the liter of water represents all the water on the earth. Pour 30 ml of the water into a second container. Ask students what they think the remaining 970 ml represents. Pour a tablespoon of salt into the 970 ml of water to help students see that the water represents the oceans. Point out on the globe or a world map the extent to which the oceans cover the earth.
- From the container holding 30 ml of water, pour 6 ml into a third container. Again look to the globe or world map and ask what the remaining 24 ml might represent (ice caps at the North Pole and South Pole).
- The third container with 6 ml of water represents that water that is not in the oceans and not part of the ice caps. Ask students if they believe the water represented by the 6 ml is usable. Ask what might make the water unusable. (Some of it is polluted; some is trapped underground and unreachable.) Ask students to estimate how much of that 6 ml is actually usable.
- With the eyedropper, put one drop of water into a fourth container. Explain that the drop represents all the useable water available on earth—8.4 million liters per person.
- Have students write a paragraph that summarizes the demonstration and the volumes of water that were used. Instruct them also to include their reaction to the revelation that such a small fraction of the earth's water is available for us to use.
- When students have completed their paragraphs, turn off the dripping faucet (or remove the jug), and record the length of time that the faucet (or jug) dripped. Keep the water in the bucket until you are ready to conduct Session 2.