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The Power of Water
Overview
The students will design and conduct an experiment to determine the effect water
has on erosion.
Grade level: 5-8
Subject areas: Science
Estimated time of completion: 2 hours
Background
Instructional Objectives
Relevant National Standards
Tools and Materials Needed
Teaching Procedure
Experiment
Assessment Recommendations
Extension Ideas
Web Resources
Background
When weathered rock and soil is moved from one place to another, it is called
erosion, and one of the most important causes of erosion is water. Naturally
gravity makes water flow downhill. The steeper the hill, the faster the water
will run, resulting in a greater rate of erosion. Faster moving water erodes
far more soil than slower moving water. Also, the amount of water has an effect
on erosion. The more water there is, the more soil and rocks that will be carried
away. In the Canyonlands, the moving water from the rivers has worn away the
rock under the rivers, which is called the riverbeds. Then the materials that
are in the moving water act like sandpaper. As they are carried along, deeper
and deeper valleys are cut. It has taken millions of years for the canyons in
the video to be formed.
Instructional Objectives
Students will have the opportunity to:
- design and conduct an experiment to determine how the amount
and rate of water flow affect the amount of erosion.
- interpret the data from the experiment to conclude the more
water there is and the faster it flows, the greater the rate of erosion.
Relevant National Standards
National Science Education Standards
http://www.nap.edu/readingroom/books/nses/html/6d.html#csd58
- Students should develop an understanding of the structure
of the earth system. Land forms are the result of a combination of constructive
and destructive forces. Constructive forces include crusted deformation, volcanic
eruption, and depositions of sediment, while destructive forces include weathering
and erosion.
- Students should develop the abilities to do scientific inquiry
and an understanding of scientific inquiry. They should be able to: design and
conduct a scientific investigation; use appropriate tools and techniques to
gather, analyze, and interpret data; develop an explanation using evidence;
think critically and logically to make the relationships between evidence and
explanations.
Tools and Materials Needed
PBS video, "Canyonlands"
TV and VCR
Soil from the schoolyard or a mixture of sand and gravel
Rectangular aluminum foil baking pan
Books
Plastic cups
Bottle of water
Graduated cylinders or four clear containers of the same size
Teaching Procedure
1. After viewing the video, ask if anyone has seen evidences of the power of
water, such as floods, dams, tidal waves, etc. and have them share what they
have seen or experienced. Did they see evidences of the power of water in the
video? (1:08:17) Ask what the narrator of the video meant when she said, "Water
is the chief architect" in the Canyonlands. Ask the students how could they determine
the effect the amount of water and the rate at which it flows would have on erosion.
2. Have the students design and conduct their own experiments.
Or give students a copy of the following experiment. (They may work in teams
of 2, 3, or 4.)
Experiment: What factors affect the rate of erosion by water?
1. Put soil into one half of a rectangular aluminum foil baking pan until is
about 2 or 3 cm deep. In the other end of the pan put a hole about the size of
a pencil.
2. Put a book under the end of the pan with the soil in it.
Put a container or a graduated cylinder under the hole.
3. Cut a small hole in the side of a plastic cup near the bottom.
Have someone hold the cup over the end of the pan with the soil. Start pouring
water into the cup.
4. Collect the water that runs over the soil in a graduated
cyclinder.
5. Put a hole in another cup at least two or three times bigger
than the first hole.. Pour water into this cup and catch the runoff.
6. Let the soil in the cylinders settle and measure the difference
in the amount of soil collected each time. Record.
7. Put another book on top of the other book to raise the pan
higher. Now is the hill steeper or less steep?
8. Repeat the same procedure using the same two cups.
9. Graph the results.
10. Analyze the results:
- How did increasing the water flow affect the amount of soil
that moved?
- How did increasing the angle of the tray affect the amount
of soil moved?
11. Draw conclusions:
- When water flows down a hill, what factors affect the rate
of erosion?
- What effects of erosion can you see in the Canyonlands?
Assessment Recommendations
Experiment Rubric
0 - no response
1 - collects data
2 - collects data accurately and represents and manipulates the data
3 - interprets data accurately
4 - generalizes, extends, and summarizes; gets the big idea
Extension Ideas
- The students might vary the kinds of soil used (clay, sand,
or a mixture of different kinds) and see what effect that has on erosion.
Web Resources
The Creation of Canyonlands
http://www.americanparknetwork.com/parkinfo/ca/geology/index.html
Center for River & Stream Studies
http://www.colostate.edu/Orgs/CRSS/
Soil Erosion
http://www.peacecorps.gov/wws/guides/lesotho/lescrisis.html#crisis
http://www.scalloway.org.uk/phye6.htm
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