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Grades: 3 to 6
Time: 45 minutes to 1 hour
Students will build
a desk-top model of a watershed to observe the path of surface water.
Students will define a
watershed as a drainage basin that collects surface water from surrounding
land. Students will describe the boundaries of a watershed as
a line formed by the highest elevations surrounding the drainage basin.
Students will identify non-point sources of pollution in their watershed
model. Students will propose best management practices to control
watershed pollution.
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Foil roasting pans or plastic boxes
Aluminum foil squares (approx. 1’x2’, or double
the size of the boxes) |
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Spray bottles containing water colored
with blue food coloring waterproof marker (sharpie) |
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"pollutant": yellow jello
to represent phosphorous |
| 1. |
Intro: Students can gently
crumple the foil to show mountains and valleys formed by plate
movements:
Flat squares of foil can represent earth’s topology before
tectonic action.
Place the foil on the desk, and place hands flat on top of each
side of the foil- (left hand on the left side, right hand on
the right side.)
Slowly slide hands together, causing the foil to crumple between.
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| 2. |
Activity: Students should fit
their gently crumpled foil into the roasting pan. Using the
waterproof marker, they can draw a line connecting the high
points surrounding large drainage basins in the model. They
might name the drainage basins to delineate different watersheds.
Use the spray bottle to "rain" on the model. Students
can observe how water travels through their watersheds, collecting
as bodies of water.
Sprinkle yellow jello onto various points of the model to represent
sources of pollution. Explain the sources, such as: |
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| a.) |
a golf course is built- it
uses fertilizers to maintain lush grass |
| b.) |
a new housing development
is created on the shore of the lake |
| c.) |
roads are built to the new
developments |
| d.) |
septic systems are installed |
| e.) |
a logging operation harvests trees from
a wooded area |
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"Rain" again on the model. Students
will observe that surface run-off carries the "pollutant"
into bodies of water in the watershed. Polluted bodies of water
will turn green when the yellow jello mixes with the blue water.
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| 3. |
Discussion: Students will observe that
pollutants can travel even from sources at a distance from their
drainage basins. This is called "non-point source"
pollution. While none of the activities were illegal, they all
had an impact on the cleanliness of the water. |
Best Management Practices
(BMP’s) can be instituted to reduce non-point source pollution.
Vegetated buffers, replanting of cleared forest, silt fencing of disturbed
areas, septic tank maintenance, and phosphate-free fertilizers are
examples of pollution reduction measures
Students might create new models to observe the
effects of BMP’s on their model.
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