The Science of Agriculture Lesson Plan
Authors:
Richard Parrish & Laura Petty
Section:
Water
Title:
Building an Edible Aquifer
Objectives:
Students will learn:
•
The components of an aquifer
•
How water is added to and taken out of an aquifer
•
To locate and identify the major aquifers of Texas
•
How groundwater can become contaminated
•
How this contamination can end up in drinking water
TEKS:
•
English Language Arts and Reading
•
Mathematics
•
Science
•
Health Education
•
Art
Supplies/Materials/Handouts Needed:
•
Picture of a cross section of an aquifer (attachment 1)
•
Picture of Texas map with 9 major aquifers outlined (attachment 2)
•
Clear punch cups
•
Napkins or paper towels
•
Clear drinking straws
•
Ice
•
Vanilla ice cream
•
Ice cream scoop
•
Lemon-lime soda
•
Green-dyed coconut
•
Chocolate syrup
•
Colored sugar sprinkles
•
Plastic spoons
•
Trash bags
Time:
20-30 minutes
Preparation for Lesson:
Review lesson content and display pictures of Texas map with 9 major aquifers outlined
and of the cross section of an aquifer.
Lesson Content:
DO
Picture of a cross section of an aquifer (attachment 1) in preparation for talking about
aquifers.
SAY
An aquifer is an underground layer of rock and soil that holds the water that we call
groundwater. The Latin meaning for aqua is water and ferre means to carry. Therefore,
an aquifer literally means “to carry water.” Ninety-seven (97) percent of the world’s
supply of fresh water is retained in such water-bearing formations.
(Could have students look up word “aquifer” to find out its meaning.)
DO
Use the picture of the aquifer to illustrate the layers of soil, limestone and other rock,
etc. of the aquifer.
SAY
Precipitation falls from the sky and lands on the earth’s surface. Some of the water runs
off into surface sources (like rivers, lakes, etc.), but some of the precipitation percolates
or filters down through the soil, pulled by gravity. This water moves through the pore
spaces surrounding soil particles until it reaches an impermeable or waterproof layer
such as rock or a layer of clay. Water begins to collect above this layer, filling the pore
spaces and saturating the area. This saturated, water holding area is called an aquifer.
The upper level of an aquifer is the water table. The level of the water table can
fluctuate depending upon seasonal changes, precipitation amounts, and the amount of
water extracted from the aquifer. Excessive pumping can reduce the level significantly.
The water table generally slopes In the same direction as the surface of the land. It is
often difficult to identify the boundaries and volume of an aquifer. In fact, most aquifers
are actually series of interconnected aquifers rather than one large aquifer.
This permits the water table to rise or drop as the level of the water changes. The
recharge area for an unconfined aquifer is local, not wide spread. This is the
most common type of aquifer.
Water derived from aquifers is critical for agricultural, industrial, and municipal
purposes. Many aquifers are becoming depleted rapidly because withdrawal rates
exceed their recharge rates. Such excessive withdrawals are called “mining” of an
aquifer.
DO
Display the picture of Texas map with 9 major aquifers outlined (attachment 2), and be
prepared to point each one out as you talk about it.
SAY
There are many aquifers found in Texas. The nine largest are the Ogallala, Gulf Coast,
Edwards, Carrizo-Wilcox, Trinity, Edwards-Trinity, Seymour, Hueco-Mesilla Bolson and
Cenozoic Pecos Alluvium. Of these aquifers, the Ogallala is the largest. It reaches all
the way from the Panhandle of Texas into Canada. It is estimated that this aquifer is
more than 2 million years old and holds about 650 trillion gallons. This aquifer is vital
for crop irrigation in the midwest portion of the United States.
(Could have students study more about the aquifers in their area.)
(To help them understand the size of the Ogallala aquifer, have the students write 650
trillion gallons, estimate how many gallon jugs would fit into your classroom, and
calculate how many times you would have to fill your classroom with gallon jugs to equal
650 trillion gallons.)
Now to finish out lesson today, we are each going to construct our own aquifer. And
what’s even better is that this aquifer is edible–that is you can eat it.
Activity:
Building an edible aquifer:
1. Provide each student with a clear plastic cup and napkin.
2. Add a layer of crushed ice to represent the rocks underground in the aquifer.
3. Add a layer of ice cream, which represents the soil, over the ice (rock).
4. Sprinkle green-dyed coconut over the ice cream to represent grass and other plants.
5. Pour lemon-lime soda (simulating rain which runs through the soil and flows down
the aquifer). The soda represents groundwater. Now we have an aquifer and
groundwater. The bottom of the cup is the layer of rock that keeps the water from
seeping down any further. The top of the water is the water table.
6. To get water out of the aquifer, have the students “drill a well” by adding a straw.
Have students sip some of the liquid. Explain that they have just simulated a well by
using their straw to “pump” the liquid from the aquifer.
7. Ask what they would have to do to bring the water table back up. Compare adding
more liquid to rainfall, which replenishes or “recharges” groundwater.
8. Squeeze some chocolate syrup and sprinkle colored sugar sprinkles over their
aquifers to simulate a contaminate like oil, gasoline, pesticides, etc. Unfortunately,
groundwater can become contaminated by improper use or disposal of harmful
chemicals such as lawn care products, trash, gasoline, and many other products when
they are not handled properly.
9. While the students are cleaning up from making their aquifers, discuss with them
other activities that could pollute the aquifer and have them come up with ways of
helping to protect our groundwater.
Conclusion:
•
What are the components of an aquifer?
•
How is water added to and taken out of an aquifer?
•
Name at least 3 of the major aquifers of Texas.
•
How can aquifers become contaminated?
•
How can this contamination end up in drinking water?
Attachment 1 - Cross Section of an Aquifer
http://www.gma.org/katahdin/aquifer.html
Gulf of Maine Aquarium
Attachment 2 - Map of Texas with 9 Major Aquifers Outlined