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Green Sparks Design Thinking Competition Key ConceptsGreen Sparks Design Thinking Competition Key Concepts


The Water Cycle

water cycle 2

Education has proven time and time again to be the answer to solving problems and creating awareness. The ability to communicate the need to protect and preserve our Lower Tennessee River Watershed can best be handled through an educational process that touches the watershed's citizens from kindergarten through adults.

The Chattanooga Watershed Academy education module is a repository of educational ideas and systems that will guide teachers, professors and community educators through an understanding of the watershed system and how we as individuals living within the borders of the watershed region can protect, preserve and enhance Chattanooga's water quality.

To better understand the importance of the natural environment and the impact it has on children The North Carolina Division of Child Development and Early Education provides an article highlighting the physical as well as psychological benefits that children can gain from spending more time outdoors.

 *Article courtesy of: (January 2012)


35701596 cloud icon on blurred background Lets start with evaporation

Evaporation allows liquid water to enter the atmosphere as water vapor. Evaporation takes place at the surface of all bodies of water, from puddles in our yards, to ponds, to Chickamauga Lake and the Tennessee River, to the seas and oceans that cover most of the Earth.  Evaporation also takes place from the surface of the soil and even from the surface of your skin.                            

When evaporation takes place from the surface of a leaf on a living plant, the process is called transpiration. Globally, transpiration contributes about 10% of the total amount of water vapor entering the atmosphere, and it is sometimes grouped with the other sources of evaporation from the environment, and the total is referred to as evapotranspiration. Evaporation will speed up if the temperature increases. Once evaporated, the water vapor becomes part of the atmosphere, mixing with the various other gasses that are present, such as nitrogen, oxygen and carbon dioxide. The water vapor can now be moved by the prevailing winds of an area.  Air saturated with moisture over the Gulf of Mexico is often diverted northward by the winds of large weather systems.

stock illustration 4879929 rain icon part of a setThen condensation  

Ultimately, this water vapor will undergo the process of condensation. As water vapor accumulates in the atmosphere, the air above can become saturated with water vapor. This condition is favorable for the water vapor to condense into water droplets. However, they cannot do this without the assistance of airborne particles, such as dust and smoke. These particles act as a catalyst for the process of condensation.  Condensation occurs when water molecules attach to fine dust particles and accumulate to form liquid water.  As these fine droplets become larger and more numerous, they form clouds.  The clouds that we see above are composed of fine water droplets (or sometimes ice crystals) that are suspended in the atmosphere.  As the droplets increase in size they become too heavy to remain suspended in the clouds, and they begin to fall to the ground in the form of rain, hail, snow, or sleet.  The term for this process is precipitation.

raining Next is precipitation

Precipitation brings the water back to the earth as rain (liquid form), or as snow, hail, or sleet (solid form). Of course, snow, hail and sleet eventually melt and become liquid water and behave as such. Precipitation may occur near the very same region where the water first evaporated. More often, however, precipitation occurs far away from the region where the water first evaporated. In North America the oceans (including the Gulf of Mexico) are the source for most of our precipitation.

From 1970 to 2000 the average annual precipitation for Chattanooga was about 55 inches. More recently however, this average value has diminished to about 53 inches per year.

images 4 leaf icon Infiltration draws it all back in

Depending on the type of surface and the amount of precipitation, when water hits the ground it may then take a variety of paths, all of which ultimately lead back to the sea. Liquid water may soak into the soil in a process called infiltration. The water will move into the spaces between the solid particles of the soil, and gravitational pull will cause the water to soak deeper into the soil until it is fully absorbed. If precipitation exceeds the infiltration capacity of the soil, surface runoff will occur. The prominence of clay soil around the Chattanooga area makes our area prone to runoff because clay has a very low infiltration capacity. Surface runoff can also occur when the soil becomes saturated with water, which happens after a long period of constant rain. This surface runoff will flow downhill and directly enter a natural water system, such as streams, rivers, and wetlands, or it may enter a man-made storm water drainage system. Storm water drainage systems are established in almost every area that has been developed in some way, such as cities, suburban neighborhoods, commercial areas, and industrial areas. Frequently, these storm water drainage systems carry surface water runoff directly to streams and river systems. Surface runoff is particularly intense in highly developed areas where buildings, paved streets, and parking lots cover most of the soil surface. These surfaces are impossible for water to infiltrate. In such areas water from rain simply has no place to go but downhill on the surface. This is one reason flooding can occur in or near developed areas.

In some cases, water may descend through the soil and enter subterranean water systems called aquifers. We refer to this subterranean water as ground water. We say that aquifers are recharged when new water from precipitation enters the underground system. The ground water in aquifers may remain relatively still, flow slowly, or flow rapidly to emerge at the soil surface far from where the water first entered the ground. In some cases, slowly moving ground water in an aquifer may take hundreds, or even thousands of years to emerge at the surface or drain into a surface water body. This depends in large part on the type of aquifer through which the water moves.

On the western margins of Chattanooga, such as Lookout Mountain and Walden Ridge, water moves through a karst aquifer. The term karst is applied to a region that is underlain with limestone that has been eroded from the inside to form a network of underground water channels. This is how caves are formed in limestone.

Through surface run-off, aquifers, streams, and rivers, all water eventually makes it back to the oceans. That's how the balance of water between the oceans, the atmosphere, and the ground is maintained, and that's why the Tennessee River never runs out of water.

 Elementary grades 2+

This demonstration is meant to help students: Define evaporation, condensation, and precipitation.

Time: 30 minutes

What you will need:

  • A beaker of boiling water
  • (2) 100 mL beakers of room temperature water
  • Small Mirror
  • Paper and markers

The day before the lesson, show the 2 room temperature beakers to the students. Ask them if they think the beakers will hold the same amount of water the next day. Why or why not? Have them explain their answers. The next day, measure the beakers. (It may take more than one day) Explain what evaporation is and then introduce the water cycle. You can demonstrate that evaporation is when water changes from a liquid to a gas with the beakers of hot water. You can also hold the mirror over the hot water beaker to show steam fogging it. Ask the students to stand squeezing close together in an open space. Tell them that in this position, they represent water molecules in liquid form; the form we drink. Let the students know that when the water gets heated and evaporates, the molecules move farther apart. Then have them spread out a little. Split the students into 2 groups. One is water, the other is air. Have them move around each other in circles. Explain that as water molecules move around in the air, they can bump into other water molecules and they will hold onto each other. You can instruct the water group to spin around until they find another water student, and then lock arms. Explain that this can also happen when the water touches something cool, as is the case with the mirror.
When the demonstration is over, ask the students to draw the water cycle in a natural setting.

All Ages

Play Watershed Jeopardy


Green Sparks Design Thinking Competition

For the creation of the outdoor classroom that educates about water qualtiy at East Lake Park, key concepts and terms for learning throughout the process are listed below.  Remember, two concepts must be demonstrated in the final outdoor classroom design.  

-stormwater pollution
-green infrastructure
-stormwater is not treated

Here are some helpful links.  Reach out to me if you would like more water quality lessons that can be used in the outdoor classroom- tell me the specific topic and I can help guide you.

Nature Conservancy's Protect Our Watersheds
Farragut Outdoor Classroom and Water Quality Demonstration Site

Philly Green Schools (nice video for teachers)
Alabama Wildlife Federation Outdoor Classroom Project
Outdoor Classroom String (larger project with more goals) but noteworthy

EPA's general Green Infrastructure

Please contact Jennifer (as listed on the Green Sparks website) to set up your class' water quality meeting and with any further questions.


Serve people with integrity and improve the infrastructure and environment through excellence.

Justin Holland, Administrator
1250 Market Street
Chattanooga TN 37402 (map)
(423) 643-6311  


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Photo by Billy Weeks