With a roll of the die, students simulate the movement of water within the water cycle.
When children think of the water cycle, they often imagine a circle of water, flowing from a stream to an ocean, evaporating to the clouds, raining down on a mountaintop, and flowing back into a stream. Role-playing a water molecule helps students to conceptualize the water cycle as more than a predictable two-dimensional path.
While water does circulate from one point of state to another in the water cycle, the paths it can take are variable.
Heat energy directly influences the rate of motion of water molecules (refer to the activity "Molecules in Motion"). When the motion of the molecule increases because of an increase in heat energy, water will change from solid to liquid to gas. With each change in state, physical movement from one location to another usually follows. Glaciers melt to pools which overflow to streams, where water may evaporate into the atmosphere.
Gravity further influences the ability of water to travel over, under, and above Earth's surface. Water as a solid, liquid, or gas has mass and is subject to gravitational force. Snow on mountaintops melts and descends through watersheds to the oceans of the world.
One of the most visible states in which water moves is the liquid form. Water is seen flowing in streams and rivers and tumbling in ocean waves. Water travels slowly underground, seeping and filtering through particles of soil and pores within rocks.
Although unseen, water's most dramatic movements take place during its gaseous phase. Water is constantly evaporating, changing from a liquid to a gas. As a vapor, it can travel through the atmosphere over Earth's surface. In fact, water vapor surrounds us all the time. Where it condenses and returns to Earth depends upon loss of heat energy, gravity, and the structure of Earth's surface.
Water condensation can be seen as dew on plants or water droplets on the outside of a glass of cold water. In clouds, water molecules collect on tiny dust particles. Eventually, the water droplets become too heavy and gravity pulls the water to Earth.
Living organisms also help move water. Humans and other animals carry water within their bodies, transporting it from one location to another. Water is either directly consumed by animals or is removed from foods during digestion. Water is excreted as a liquid or leaves as a gas, usually through respiration. When water is present on the skin of an animal (for example, as perspiration), evaporation may occur.
The greatest movers of water among living organisms are plants. The roots of
plants absorb water. Some of this water is used within the body of the plant,
but most of it travels up through the plant to the leaf surface. When water
reaches the leaves, it is exposed to the air and the sun's energy and is easily
evaporated. This process is called transpiration.
All these processes work together to move water around, through and over Earth.
Using station illustrations, create a one page graphic on which students record their movements during the Incredible Journey.
Ask students to identify the different places water can go as it moves through and around Earth. Write their responses on the board.
Have students use their travel records to write stories about the places water has been. They should include a description of what conditions were necessary for water to move to each location and the state water was in as it moved. Discuss any cycling that took place (that is, if any students returned to the same station). Provide students with a location (e.g., parking lot, stream, glacier, or one from the human body-bladder) and have them identify ways water can move to and from that site. Have them identify the states of the water.
Have older students teach "The Incredible Journey" to younger students.
role-play water as it moves through the water cycle (step 8).
identify the states water is in while moving through the water cycle (step 4 and Wrap Up).
write a story describing the movement of water (Wrap Up).
Have students compare the movement of water during different seasons and at different locations around the globe. They can adapt the game (change the faces of the die, add alternative stations, etc.) to represent these different conditions or locations.
Have students investigate how water becomes polluted and is cleaned as it moves through the water cycle. For instance, it might pick up contaminants as it travels through the soil, which are then left behind as water evaporates at the surface. Challenge students to adapt "The Incredible Journey" to include these processes. For example, rolled-up pieces of masking tape can represent pollutants and be stuck to students as they travel to the soil station. Some materials will be filtered out as the water moves to the lake. Show this by having students rub their arms to slough off some tape. If they roll clouds, they remove all the tape; when water evaporates it leaves pollutants behind.
Alexander, Gretchen. 1989. Water Cycle Teacher's Guide. Hudson, NH: Delta Education, Inc.
Mayes, Susan. 1989. What Makes It Rain? London, England: Usborne Publications.
Schmid, Eleonore. 1990. The Water's Journey. New York, NY: North-South Books.