|OBJECTIVE||Students will learn how the water cycle works using 3-D paper craft activity.|
|TOTAL TIME||40 minutes|
|SUPPLIES||Scissors, scotch tape or glue, colored pencils
|PRINTED/AV MATERIAL||Water Cycle paper craft (pdf). With labels. Without labels. (printed on 8½x14" paper)
Optional: full color version.
|TEACHER PREPARATION||Regular copier paper can be used. For a sturdier model use card stock. The pdf can be scaled down to fit letter-size paper but the model will be very small and more difficult to assemble. You can bypass the coloring part of the activity by printing the full color version.|
|SAFETY FOCUS||Flash Flood Safety|
Water moves from the ground to the atmosphere and then returns to the ground, however, the actual path water takes in its cycle is more complicated. There are many stops on water's journey.
- The paper craft consists of two sections: the 'earth' and the 'atmosphere'. First have students color their water cycle paper craft. They can use this image as a guide for color choices.
- If using the un-labeled pdf have the students add labels while you discuss the function of each portion of the water cycle. (see discussion below). The 'surface flow' label in the mountain region should be added upside down so it will display correctly when the paper craft is assembled.
- Carefully cut out both base and atmosphere sections. Cut only along solid lines. DO NOT cut dashed lines.
- Fold paper craft along dashed lines.
- Beginning with the base, line up tabs with fold and carefully tape or glue tabs to their corresponding surface. If using glue, use sparingly. Using too much glue will warp the paper.
- Attach the atmosphere cutout to the back side of the paper craft.
- Optional: glue small pieces of cotton balls over the clouds on the atmosphere cutout.
The water cycle is more complicated than is depicted in typical diagrams. Often the diagrams show water evaporating over the ocean then moving onshore before precipitating. Actually, evaporation and precipitation occur all over the earth and can occur at the same time in the same location. This process is why humidity increases during precipitation and the liquid evaporates back into water vapor.
The water cycle and is divided into three main parts:
- Moisture moving into the atmosphere
- Moisture moving through the atmosphere
- Moisture returning to the earth
Since water covers nearly 71% of the Earth's surface, the greatest source for moisture are these huge water bodies.
Evaporation is water changing from a liquid to a gas. Evaporation requires a source of heat. The sun is the primary engine for evaporation. On average, about 47 inches of water (120 cm) is evaporated into the atmosphere from the ocean each year. Your body's heat causes water on your skin to evaporate. That why you feel cold when you step out of a pool or shower. Your using your body's heat to dry off.
Sublimation is the change of state from ice, a solid, to water vapor, a gas, without becoming a liquid first. Given enough time, snow and ice will disappear by sublimation.
Transpiration is evaporation of water from plants and trees into the atmosphere. Nearly all (99%) the water that enters the roots transpires into the atmosphere.
Once in the atmosphere water vapor can undergo the following changes.
Condensation is the change of water vapor, a gas, into liquid. We see the end result of condensation as clouds which consists of huge numbers of tiny liquid drops. The clouds can also undergo evaporation, returning the liquid back into a gas.
Transportation is the motion of moisture as a result of the wind. Without this movement, the water evaporated over the ocean would not precipitate over land.
The moisture returns to the earth two ways.
Deposition changes water vapor directly into a solid (ice), bypassing the condensation process. This process is how frost forms on cloudless winter nights. When the sun rises, most of the frost will again evaporate or sublimate back into the atmosphere.
Precipitation returns water to the earth as rain, snow, ice pellets (sleet) and hail.
The water returns to the ocean in one of four ways.
Infiltration is the movement of water into the ground from the surface. Simply put, the ground gets wet and muddy. The moisture then evaporates into the atmosphere or trees and plants use some of the moisture, which they later return to the atmosphere through transpiration.
Percolation is water seeping sown past the soil, deep into the ground water.
Surface Flow is water that does not move into the soil but instead runs off into creeks, streams, and rivers to flow back to the ocean.
Groundwater Flow is underground water flowing (aquifer) back into the ocean. Sometimes the underground flow pops up at the surface and create a 'spring'. Water from the underground flow also moves in and out of lakes.
All of these processes are happening constantly. What is left out of the water cycle above is the human and animal component. Moisture taken in by the body is used to move food and blood around our bodies then eliminated back into the environment in many different ways.
When there is too much rain in a very short time, sewers are not able to keep up with the surface runoff, creates flash flooding.
Flash floods are the deadliest natural disaster in the world. They are usually caused by thunderstorms that stay over one area for a long time and produce heavy rain over a small area. Hilly and mountainous areas are especially vulnerable to flash floods, because steep terrain and narrow canyons funnel heavy rain into small creeks and dry ravines, turning them into raging walls of water. Even on the prairie, normally-dry low spots can fill with rushing water during heavy rain.
Take time to develop a flood safety plan for home, work, or school, and wherever you spend time during the summer. For more information and safety tips, see the National Weather Service flood safety website and download "Floods and Flash Floods...The Awesome Power".