Erosion lab
Prediction:
How does rain shape the Earth?
Here's what you'll need:
• 2 large disposable aluminum lasagna pans
• Some good old fashioned dirt (natural soil from a garden, NOT potting soil from a bag)
• Glassware
• 2 or 3 books or wooden boards about 1/2-inch thick each
• A pair of pointy scissors or the needle of a drawing compass
Here's what to do:1. Pour the dirt into one of the pans so that it makes a layer on the bottom 2 to 3 inches deep. Smooth the soil out so that it is as even as possible on the top.2. Examine the soil closely with the magnifier. Touch it and run it through your fingers. What is the soil made of? Does it all feel the same? How do you think the different soil parts would react if water was poured on them?3. Use the scissors or compass needle to punch 6 small holes in one end of the tray.4. Place the second pan under the end of the dirt-filled pan where the holes are. (The second pan will catch the water as it leaves the top pan.)5. Slip 2 or 3 books under the other end of the dirt-filled pan so that it is propped up about 2 inches higher than the end with the holes punched in it.
Pour water from the watering can into the raised end of the dirt-filled pan.
1. What happens to the surface of the dirt when the water first hits it?
2. What happens to the water that comes out of the dirt-filled pan and collects in the second pan?
3. Do you think it matters if the soil starts out wet or dry?
4. What would happen if you added a few more books under the pan to make a steeper slope? Do all the soil particles get pushed equally by the water? (Note: Make sure you carefully study the soil first because not all dirt is created equal!)
5. Do humans create erosion?
Share your results with the rest of your class.
Conclusion: Write a CER (Claim Evidence Reasoning Paragraph)
Claim: Water erodes Earth's Surface.
Evidence: (Provide at least 2 pieces of evidence)
Reasoning: (How do you know that your evidence proves that water erodes the earth)
Adopted from: Scholastic Dirtmeister
Related Resources:
Environmental Studies
This site, created by high school students, focuses on seven different environmental topics of interest: animal populations, beach studies, people vs. pests, traffic analysis, water studies, wetlands, and the legitimacy of Superfund, funds set aside for the cleanup of hazardous waste sites.
http://www.bergen.org/AAST/Projects/ES/index.html
Global Change
Real-world data and lesson plans that allow students to analyze and use data that provide an introduction to the concepts of environmental changes to the Earth and their causes and effects. The activities include time and cycles, change and cycles, mud fossils, geologic age, and the Earth as home.
interactive2.usgs.gov/learningweb/teachers/globalchange.htm
Surfrider Foundation, USA
This is the home page for the nonprofit Surfrider Foundation, which seeks to protect, preserve, and restore the world's ocean and beach environments. Daily weather and wave data, photographs, facts, and updates on environmental projects are provided.
Extensions
Here are some suggestions to enhance the experience of Dirtmeister's Science Lab for your students:
Extensions on Erosion
Observe an actual field area before and after a rainstorm to see if any erosion has taken place. Look for places where the water has cut little channels in the soil, or where small piles of sand has been deposited.
After a storm, water in a pond can stay turbid for several days due to suspended clay particles. Scientists measure turbidity using a device called a "Secci Disc," but students can make their own "mud meter" by taking a white piece of plastic and painting black stripes on it. Tie a fishing weight to the bottom of the disk and slowly lower it into the water until it disappears. Measure the length of the string below the water surface and record the depth. Come back a few days later and repeat the experiment. If the water has cleared up, they should see the disk in the water to a deeper depth.
Soil texture (the relative combination of sand, silt, and clay present in the soil) differs from one area to another. To see how different soils "stack up," take a one-quart glass jar with a lid (a mayonnaise or pickle jar works great) and fill it about 3/4 full of water. Add 1 cup of soil and shake for 10 seconds. Allow the soil to settle for a few minutes and you will see different layers appear. The coarse material (about the size of sand) will settle to the bottom first, followed by the silt and then the clay. By looking at the relative thickness of each layer, they can get a sense of what their soil is made of. Try a bunch of different soils to see how each "stack up."
Where does the sand on a beach come from? Why are rocks in a stream usually round? Most people don't realize it, but soil starts out as rocks. These rocks have been broken down by a process called weathering. If you want to see weathering in action, take 3 or 4 small rock specimens and put them in a large plastic container filled half way with water. Place a lid tightly on the container and have the students take turns shaking it as hard as they can. Do this for a total of 10 minutes. Open the lid and look inside. Where did the dirty water come from? Did any of the rocks change shape? They'll quickly discover how rocks can roll and in the process make sand!
Have the class use the computer to search the web for supplementary articles on soil erosion and its protection. A good place to check is the USDA Soil Conservation Service.