Lesson Plan by who has taught science at both the middle school and high school levels for Lincoln Public Schools. She has written assessment and curriculum for LPS and has attained a Level II assessment certification. She has also served as a student teacher supervisor for the University of Nebraska-Lincoln.
|Suggested Grade Level:
Logical-mathematical & Naturalist
|What are these educational concepts?|
In this lesson, students will:
- build and view a model aquifer;
- define and explain what they have observed from using a scientific model;
- learn to differentiate an explanation from a description.
Where does groundwater come from? When rain falls and snow melts, some of it flows along the surface of the ground into streams as runoff. Some evaporates into the air, some is taken up by roots and some soaks into the ground to become groundwater.
Underground areas called aquifers collect much of this groundwater. An aquifer is an underground layer of sand, gravel, or permeable rock that collects water. As water seeps down through the soil, it eventually hits a solid layer. The aquifer forms as groundwater collects in this impermeable layer.
The size of an aquifer depends on at least tow things: 1) the amount of rainfall, and 2) the composition of the underground soil and rock. The world’s largest aquifer is in the United States, called the Ogallala. It spreads under eight states from South Dakota to Texas. The Ogallala formed millions of years ago and is still supplying water to cities, farms and businesses.
In this activity, you will build a model showing how water is stored in an aquifer. You will also see how groundwater can become contaminated.
Links from within the Wessels Living History Farm site. [Note that clicking on these links will open a new browser window. Just close it and you’ll be back to this page.] Direct the students to these pages.
Resources from outside Wessels. Direct students to these Web sites and books that are produced by others outside of the Wessels Living History Farm. [Again, clicking these links will open a new window.]
- The U.S. Environmental Protection Agency (EPA) has a Ground Water Primer here, http://www.epa.gov/seahome/gwprimer.html.
- Opie, John, Ogallala, Water for a Dry Land. University of Nebraska Press, 2000.
Materials needed for the Experiment
- Clear, plastic container (at least 15cm deep)
- Modeling clay (one pound)
- Play sand (2 pounds)
- Aquarium gravel or pebbles (2 pounds)
- Clear drinking straw
- Plastic spray bottle
- Green felt (index card size)
- ¼ cup powdered cocoa or powdered drink mix
- Food coloring
- Clean water
- To create the “well,” tape the straw inside the plastic container along one side, vertically. The bottom end of the straw should not touch the bottom of the container.
- Pour a 3-4cm layer of sand on the bottom of the container.
- Pour water onto the sand. The sand should be completely wet but not have puddles. The sand should absorb the water.
- Flatten the clay and cover ½ of the sand with it. The clay represents the impermeable layer that where water cannot pass. Press the clay to the sides of the container.
- Pour a small amount of the water onto the clay. Some should flow over onto the uncovered sand.
- Use the rocks to cover the sand and clay surface. Slope the rocks on one side to create a hill inside the model.
- Fill the container with water until the water is even with the top of your hill. Notice how the water becomes “stored” around the rocks. You should also have a small lake forming at the surface. At this point, the model represents groundwater and surface water. Both can be used for drinking.
- With a partner, put a few drops of food coloring into the straw to represent pollution. The food coloring should color the sand, representing how pollution can spread through an aquifer.
- Place the felt on the “hill.” You may need to use clay as a fastener.
- Sprinkle cocoa or drink powder on the hill to represent the misuse of chemicals or fertilizers.
- Make it rain on the hill using a filled spray bottle. Spray on the hill and over the aquifer. The powders should seep through the felt and wash into the surface water. This represents another way for pollution to reach an aquifer.
- Observe the area around the straw. Make a note of where the pollution has spread. Devise a way to pull water up from the well, but do NOT drink the water used in this lab. How does the water look? Remember that this is the same water that people drink.
Do NOT drink the water used in this lab.
You may wish to spread topsoil over the sand or gravel to make a more realistic model of farmland.
Conclusion of the Lesson
Today, over 70 percent of the cities in the United States depend on groundwater for part or all of their drinking water. Wells also withdraw groundwater to irrigate crops and meet recreational needs. When water is pumped out of an aquifer into a well, the water level drops. If water is not replaced by rainfall, the aquifer becomes overdrawn.
Read the assigned bibliography and write two to three questions based on the information given.
Write a paragraph explaining what you observed from this model.
Draw a side-view picture of the model aquifer and label the following: bedrock groundwater, lake, pond, water table, soil (land), and well (deep well).
Answer the following questions as a team and record the best answers:
Why are the results from the model not measurable?
How could the design be altered to get a measurable result?
What could you do to the model to simulate a drought?
What are the contaminants in your local water?
Is water a renewable resource?
Sketch a map of the states covered by the Ogallala aquifer. How do scientists keep track of the water in the aquifer?
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