Canyonlands - America's Wild West Teaching Canyonlands

The Power of Water

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

Instructional Objectives

Relevant National Standards
Tools and Materials Needed
Teaching Procedure
Assessment Recommendations
Extension Ideas
Web Resources

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

  • 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
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

Center for River & Stream Studies

Soil Erosion

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