This experiment, adapted from Janice Van Cleave's Earth Science for Every Kid, p. 164, is a fantastic demonstration of the water cycle. It allows the students to see what really happens in the cycle in just a short time. Surely every student has seen clouds and rain, but some students may still have trouble relating the rather scientific concepts of "evaporation" and "condensation" to the clouds they observe every day in the sky. Therefore, this experiment is helpful because students can observe evaporation, condensation, and "rain drops" in just about ten minutes. For a great explanation of the science behind the water cycle see page 140 of The Best of Wonder Science.

If this experiment comes at the beginning of a unit on weather or the water cycle, ask the students the following questions to get them thinking: Why does it rain? Where does the water that rains on us come from? Where do the clouds come from? etc. . . (They may be reluctant to answer if they feel that they don't know anything, but encourage them to keep brainstorming. Their experiences and observations of daily life have probably taught them a lot more than they realize. Proving this to themselves will be a great confidence booster.) Have the students respond to these questions first individually in their notebooks. Then have them pair up with the student next to them to discuss their individual opinions. Finally, ask for volunteers to share with the whole class what they think based on the collaboration with their partners. Hopefully this exercise will help whet their appetite to find out more what happens in nature.

water

cycle

oceans and lakes

evaporate

condense

atmosphere

clouds

rain drops

for each student or group of students:

• -( 1) glass jar with a metal lid (peanut butter or jelly jar works great)
• -(3) ice cubes
• -enough tap water to cover the bottom of the jar (room temperature water will work, but the results are quicker and more dramatic with hot water
• -paper and pencil to record observations

If there are enough jars, it would be great to have the students work individually; otherwise, divide the class into small groups to perform the following steps:

Cover the bottom of the jar with water to a depth of 1-2 cm. Turn the medal lid upside down and place on top of the jar. Place the three ice cubes inside of the lid. (see picture to the right) Record anything and everything you notice for the next ten minutes. After about ten minutes, take the lid off and observe the underside. Record observations.

Make sure each student can describe the water cycle either orally or written using the vocabulary above.

A creative way to assess their understanding is to have them write a story from the point of view of a water molecule as it travels through the water cycle. Ask them to be as detailed as possible so that it's obvious they understand the water cycle but encourage them to have fun with the creative details of the story. (Adapted from the Science curriculum standards for Philadelphia Public Middle Schools)

A great extension could be for the students to find out more about water -- it's properties, its uses, how to conserve it, etc. After they have investigated water more thoroughly, they could do a final project on water in any form they choose -- e.g., collage, drawing, story, poem, or even acting out the role of water! Some suggestions for topics for the project are: "the uses of water", 'what would life be like without water?" etc. Let their talents and creativity flourish!

Walter Wick's A Drop of Water is a fascinating book about water. It has really neat pictures and descriptions of all the amazing things water does. If the class had a copy of this book, the students could explore it on their own if they finish work early.

SCIENCE CONTENT STANDARD #1: NATURE OF SCIENCE

This experiment satisfies Benchmark 1 for grades 5-8: "conduct an investigation which leads to a better understanding of how things work." It also satisfies Benchmark 3 for grades 5-8: "collect and summarize data from an experiment and interpret the results in terms of the data."

SCIENCE CONTENT STANDARD #2: PHYSICAL SETTING

This experiment satisfies Benchmark 3 which states that students should "understand the effect of the . . . water cycle on natural resource management". The section in the Extensions" involving when to water a garden especially ties in with this benchmark. Furthermore Benchmark 7 states that students should "understand that the cycling of water in and out of the atmosphere plays an important role in determining climatic patterns. Water evaporates from the surface of the earth, rises and cools, condenses into rain or snow, and falls again to the surface. The water falling on land collects in rivers and lakes, soil, and porous layers of rock, and much of it flows back into the ocean."

Although this lesson fits best in an earth science unit dealing with the water cycle, it could also tie in with a unit on weather or a unit on water in general. It could also fit into a unit on phase changes. Finally, the more creative the students get in their final projects (see 'Extensions section), the more this lesson would also incorporate writing and drawing skills.