Soil Erosion - Juniata College

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Juniata College
Science in Motion
Middle School
Soil Erosion by Water
Grade Level(s): 6-8
Introduction:
Sediment is the most abundant pollution of PA streams. Run-off of
soil after a heavy rain is a major concern for PA farmers,
construction companies, and land-owners in general.
Subject(s): Science/Environmental Education
Duration: 40-80 minutes
Safety:
Students should use caution to not spill the soil or the water and clean area
properly.
Description: Using a conceptual change model, students will make a
connection between soil erosion by water and the effects it has on the rain
forests.
Goals: Students will identify the relationship between soil erosion by water
and the erosion of PA soils and pollution of PA waterways.
Objectives: Students will:
Observe that soil erosion occurs when the water washes the soil away from the
trays by completing the following procedure.
1. Place sand, soil, with or with-out grass, leaves (litter) or any combination of
the above in the plastic container/s and/or stream table.
2. Pour water in the container at the highest elevation.
3. Observe the time (with a stop watch) it takes for the water to start running
out the bottom of the container.
4. Record the color of the water that is coming out of the container (1 nearly
colorless and 10 is the most muddy)
5. Record the length of time until most of the water has stopped flowing from
the container
a. Record the data in the chart provided
b. Develop a general scientific understanding that plants hold soil in
place via roots and help prevent soil erosion by water.
6. conclude that soil erosion by water increases with the removal of plant
matter
Materials:
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bins (containing soil; water; graduated cylinders; 5 trays: 1 tray with
grass growing in soil, 2 with just soil, 2 empty; ruler; paper towels; rubber
bands)
buckets for catching overflow
Earth Science Stream table by Science Kit and Boreal Labs
Booklet for above
journals
overhead projector
markers and pencils
Procedure:
Instructional Method:
1. Divide class into groups of 4.
2. Students will be given the question : Which will displace the greatest
amount of soil when the same amount of water is poured on to each one.
3. Students will first individually hypothesis what container will displace the
greatest amount of soil and why.
4. Students will then perform the experiment. They will determine whether
the soil displaced is high, medium, or low.
5. Students will respond to the following questions in their journals: What
happens when soil erosion occurs by water?
Scientific Explanation:
The central scientific question to be answered by students is: What occurs
when rain falls on to soil that contains no plants? Why does this happen? Soil
erosion occurs when unprotected soil is washed away by rainfall. Plants
prevent soil erosion by stabilizing the soil with their root systems.
Focus Phase:
The students will draw and describe in their journals what they think will
happen when we pour one liter of water on a tray of soil with plants and a tray
of soil without plants. Then the students will share their hypothesis with their
groups and then the class. We will chart the hypothesis on board.
Challenge Phase:
1. Tray A will have the soil w/ the grass.
2. Tray B will have the tray w/ only soil with litter (grass/ leaves).
3. Tray C will have soil only.
4. Tray D will have only sand.
Tilt all of the trays with science books so that one end is higher than the
other.
5. All trays need to be tilted the same.
6. Put the waste bucket under the vinyl tubing so as to catch the water
from the stream table.
7. Pour water into all of the trays using the provided watering containers.
The students will answer the following questions.
8. Which tray displaced the most soil?
9. Why do you think this happened?
10. Students will also record their information on a data table provided by
the teacher using the following categories.
Amount of Soil Displacement
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Observe the amount of soil that is displaced (moved form one place to
another) in your stream table.
A high level of soil displacement will be represented by a handful of soil.
A medium level will be half a handful of soil and low levels will be
represented by a pinch of soil.
Complete the following chart while performing the soil erosion lab.
1. Hypothesis: Which stream table do you think will loose the most soil
due to water erosion?
2. Which tray displaced the most soil?
3. Why do you think this happened?
4. Complete the following table. Put an X by the stream table that your
group tested.
Type of
Soil
Sand
Bare Soil
Soil with
grass
Soil with
litter
(leaves)
Start
Time
End Time
Total
Time
Water
Ending
Conditions Amount
of Water
Soil Erosion
Teacher Page:
Introduction:
Concept Introduction:
Refocus students by asking what is the term used to describe what just
happened with the soil?
Erosion. How does erosion occur?
The water pushes the unstable soil.
Soil erosion occurs when unprotected soil is washed away by rainfall.
Why was there less soil eroded from the container with the grass?
Plants prevent soil erosion by stabilizing the soil with their root systems.
The roots grab a hold of the soil. As a class, we will write a general
scientific understanding.
Concept Application:
First have the students hypothesis what they think will happen when we
do the problem below and why.
Problem: Build a hill made out of soil and then pour a cup of water on it
and write in our journals of what happened. Also in our journals we will
respond to the following by using our scientific understanding of erosion:
Imagine this is a hill in the rain forest. What is a way to prevent a land
slide from occurring?
Assessment:
In students’ journals they will develop a hypothesis of what would happen to
the land and the animals of the rain forest when the trees are cut down and
destroyed? Why? The students will have time to share their ideas with the
class.
Standards
Science and Technology
3.5 Earth Science
3.5.7A Describe earth features and processes.
 Describe the processes involved in the creation of geologic features
(e.g., folding, faulting, volcanism, sedimentation) and that these
processes seen today (e.g., erosion, weathering crustal plate movement)
are similar to those in the past.
 Describe the processes that formed Pennsylvania geologic structures
and resources including mountains, glacial formations, water gaps and
ridges.
 Explain how the rock cycle affected rock formations in the state of
Pennsylvania.
 Distinguish between examples of rapid surface changes
(e.g., landslides, earthquakes) and
slow surface changes
(e.g., weathering).
Environment and Ecology
4.1 Watersheds and Wetlands
4.1.7A Explain the role of the water cycle within a watershed.
 Explain the water cycle as it relates to a watershed.
4.1.7B Understand the role of the watershed.
 Explain how water enters a watershed.
 Explain factors that affect water quality and flow through a watershed.
4.1.10A Describe changes that occur from a stream’s origin to its final
outflow.
4.1.10B Explain the relationship among landforms, vegetation and the
amount and speed of water.
 Analyze a stream’s physical characteristics.
 Describe how topography influences streams.
 Explain the influence of mountains on precipitation.
 Explain how vegetation affects storm water runoff.
 Delineate the boundaries of a watershed.
 Describe factors that affect the quality of groundwater.
 Explain how the speed of water and vegetation cover relates to erosion.
Lab Time:
One or two 40 minute periods
Preparations:
Set up stream tables and student stream tables.
Acquire leaf litter, grass, sod or other ground cover
Considerations:
This lab could be dirty. Care should be taken to minimize contamination of
the floor and other surfaces as well as clothing.
Use the waste water buckets to catch water draining from stream tables.
Students should already know:
Water is the main cause of erosion.
Sediment is the most abundant type of water pollution in PA.
Sediment that is carried to streams will take with it all other available types
of pollution
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