The same ole water
Time: 1 hour Best location: indoor/outdoor Materials:
2 water cycle handouts/or transparencies
The teacher/leader can write the following statement on a posterboard or the chalk board:
"The water we use today is the same water the ancient Egyptians used thousand of years ago."
Ask the students to debate whether this statement is true or false. Undoubtably, this will raise some questions.
Using the handout, and/or the transparencies, explain the cyclic process to the children. Explain that falling rain is one part of the cycle. The rainwater comes from water which is evaporated from the land and water. Water is heated by the sun, rises to higher altitudes, cools sufficiently to condense into clouds and finally falls back to the earth as precipitation. The precipitation which falls on the land is taken up by vegetation and also percolates down through the soil. This ground water flows into rivers, streams, and lakes and is then exposed to the sun to be evaporated once again. Water is also given off from the vegetation through the process of transpiration. The evaporated water cools as it rises until it condenses into clouds, completing the cycle.
The teacher/leader should help the students to see that the water cycle is a closed system. It goes around and around with the same water we have had always. Emphasize that we will never have more water on Earth than we have now and thus the importance of protecting this precious resource.
The second handout/transparencies is a simplified illustration of the water cycle in the urban environment. The children may not be aware of the cyclic process of their water usage in the city. Ask your students how the water cycle in nature might be altered in the urban environment. For example, what happens to the rain that falls onto the school blacktop and city streets? Since the water can't percolate down through the concrete, where does it go? You may want to take advantage of the next rainstorm as an opportunity to observe the water cycle in action. Go out during or after the rain and watch how the water runs off the playground, sidewalks, and streets into the storm sewers. Look at the puddles that have formed and discuss the process of evaporation.