Suggested use of 2 Hour Class Day:
-15 min set-up
-15 min introduction
-4 Centers, 20 min. each
-15 min conclusion
Introduction
Please keep an
eye on the
“drying” sand bin
in the ELF
closet. Stir often
to facilitate
drying – if you’re
there for lunch, a
doc appt., or
otherwise,
go give the sand
a stir!!
1
ELF
Erosion
April 1, 2013
Focus:
The landscape continually changes over time due to forces of weathering and erosion by water (e.g.,
rain, rivers, groundwater, waves), wind, gravity, ice, and organic activities of animals, plants and humans.
Opening Question:
What is erosion, and how does it shape the landscape?
The slide show provides an effective opening. The CD and script (K-2 and 3-6th versions) are in the ELF
intro/conclusion bin. If necessary: please arrange laptop loan with the LMC prior to your ELF date. Remember to
hit “pause” when first slide cues.
Prior to or instead of the slide show, you might choose to discuss a few of the following concepts:
 Ask the students if any of them have run water into their sandbox. What happened to the sand? Show them
a picture of the Grand Canyon and of a gully in the mud bank. Could both these features be formed the same
way? Ask how these features were formed (running water). Could the Grand Canyon really have formed by
water carrying away sand and pebbles? What are other examples of weathering and erosion by water?
Ocean waves erode the shore. Caves form when underground water dissolves limestone. What about frozen
water? Giant masses of packed snow and ice called glaciers grind away land to form valleys and lakes.
 What other forces cause erosion? Wind? (Important in dry climates like deserts, it “sandblasts” rocks.)
Gravity? (avalanches, landslides) Plants? (Roots crack open rocks.)
 Do animals contribute to erosion? How do human activities affect erosion?
 When soil, sand, and rocks are eroded from one location, where do the materials end up? You can connect
this unit with the previous unit on rocks by showing a rock cycle diagram and discussing how weathering and
erosion fit into the rock cycle.
 Since rocks and soil are constantly eroded, why are there still mountains? Why doesn’t all land erode away
and end up in the sea? (Mountains are formed by uplift of molten material from inside the earth.)
 What can prevent erosion? Can people prevent erosion? Why might you want to prevent erosion?
 A fun way to distinguish weathering, erosion and deposition are with the phrase “break, take and make.”
Weathering breaks down rock to sediment, erosion takes it away, and deposition makes new landforms.
ELF Intro Bin:
 Five puppets
This puppet show follows Ricky Rock and Billy Boulder as they experience different kinds
 Sheet for stage
of changes through weathering and erosion. There are six speaking parts; one is a voice
with no puppet. One puppeteer could do both Ricky and Tiny Ricky, and another could do  Spray bottle
both Billy and Tiny Billy (using higher voices for the tiny versions).
Puppet Show
Afterwards, review with students the forces of erosion identified in the show: glaciers,
gravity, rain, rivers, human activity (tree cutting), wind, and waves.
2
Centers – there are SIX centers, you only have time for FOUR.
Center 1: Shaping the Land/Blowing in the Wind
Shaping the Land
Objective: To identify examples of weathering and erosion and their causes.
Show pictures of land changed by erosion. The photos show features formed by various
agents of weathering and erosion: wind, moving water (ocean, rivers, runoff), gravity, as
well as the effects of animal and human activities on erosion. Have the students discuss
each photo: how the processes of erosion affected these landforms. Each photo has a
key on the back. Point out how the landforms caused by wind erosion relate to the
previous experiment. Several forces may work together – there are no real wrong
answers. Use photos from books, such as Shaping the Earth – Erosion by Downs and
Erosion by Rutten, to supplement this activity. If time permits, you might review the
laminated articles.
If you do not wish to use the photos for this center, you may want to use them in the
closing or as examples of erosion in another center (Center 2?).
Blowing in the Wind
Objective: To explore the effects of wind eroding the landscape.
If there is sand in the plastic tub, pour it into another container. Place a few small items in
the tub (penny, bell, etc) and then pour in about an inch of dry sand. Cover the pan with
the plexi-glass and give each student a straw. Ask the students what will happen to the
sand if they blow the sand using the straw. Have the students take turns to insert a
flexible drinking straw, bent at nearly 90 degrees, through the hole in the plexi-glass and
blow the sand. Encourage them to move the straw around in different directions, noticing
places where sand builds or gets hollowed out. Students should not share straws.
Where might this type of erosion occur? Ask what will happen if the surface of the sand is
moistened with water. Then, remove the plexi-glass and let them use a spray bottle to
dampen the sand lightly (3-4 sprays). Replace the cover and let the children try to blow
the sand again. What happens differently this time? Afterward, ask them in what
environment is wind most effective as an agent of erosion? Discuss how wind affects
deserts, sand dunes, and beaches. Discuss why wind might cause more erosion in a
desert that in a jungle. Can wind wear down rocks? Discuss how wind picks up sand and
“blasts” rocks, wearing them away like a sandblaster. This is called “abrasion.”
After each group, pour out the damp sand into the drying bin and replace with dry sand.
When all rotations are completed, leave the sand in the plastic tub to dry.
Center 1 Bin
 Soda Straws
 Plastic tub
 DRY Sand
 Plexi-glass w
holes
 Spray bottle
 Misc. small
items to bury in
sand
 Container for
damp sand
 Laminated
photos
 Laminated
Formation of a
Sand Dune
 Laminated
Chemical
Weathering
 Laminated
Chemical vs.
Physical
Weathering
 Books: Sand
Dunes by
Bannan; Sand
on the Move by
Gallant; Sand by
Prager.
Please keep an
eye on the
“drying” sand bin
in the ELF
closet. Stir often
to facilitate
drying – if you’re
there lunch, a
doc appt., or
otherwise,
go give the sand
a stir!!
3
Center 2: Erosion Hunt
ELF Center 2 Bin
 Laminated
Objective: To discover signs of erosion and weathering on the school grounds.
“Erosion”
drawings
Especially for the first rotation, you might begin by showing the group erosion photos from

Laminated:
the laminated sheets or from the books..
erosion web

Laminated:
Then take the students outside to look for effects of erosion and weathering around the
Weathering and
school grounds. Good examples may be found near drains and at the edges of black tops.
Erosion Venn
Look on the hill south of the school between playgrounds and directly behind the school
Diagram
(on the side down the stairs) for signs of water runoff, human impacts, and the role plants

Maps of school
play. What is the effect of fences? Look for worn pathways in the dirt, erosion around
 Clipboards
downspouts, crumbling edges of blacktops, chipped paint, and cracked concrete. Also
look for rust – caused by oxidation, a form of chemical weathering. Discuss possible
agents weathering the different sites. Where is the eroded material going? Look for signs Classroom
of deposition, around downspouts and below runoff features. What could be done to slow  Pencils
or prevent the erosion they see? What has been done? (Gravel, netting, terraces,
 Paper (optional)
retaining walls, sealant in cracks, concrete gutters, diverters below downspouts). How
does gravel affect erosion? Grass and trees? You might find potholes on the adjacent
road or parking lot. Discuss the weathering impact of repeated freezing and thawing of
water that seeps in to cracks in roads or rocks (freeze wedging).
Discuss how plants, animals, and people affect erosion. Then discuss how erosion affects
the plants and animals that live in the area. What can be done to slow down or prevent
erosion on the school grounds? Ask the students to describe specific erosion sites,
discuss whether something should be done to prevent further erosion, and if so, what
ideas do they have?
With younger students, simply explore the grounds, discussing the features that are found.
Allow them to sketch the erosion features on paper, if they wish. For older students, hand
out clipboards and the maps of the school grounds. Have students mark the locations
where erosion is taking place, noting what forces are at work (e.g., water runoff) with
different symbols of their own design, including a key to their symbols.
Alternatively, kids could write or sketch their ideas for erosion control at Mitchell.
4
Center 3: Splash
Objective: To discover the power of raindrops on the earth.
This is a floor space center. Begin by asking how raindrops might cause erosion. Since
each raindrop is small, can it contribute significantly to erosion? What about the combined
effects of heavy rains over time? What might rain do to loose top soil? Explain that this
center will involve experiments to show how raindrops cause weathering and erosion on
materials representing different soil types (flour, sand and gravel for fine to course soil
types). Set the plastic table cloth on the floor and then set down one of the blue plates
with waxed paper on it. Place only a spoonful of flour in the center of the sheet on the
waxed paper. The flour represents dry, fine soil.
Ask for predictions of what will happen when a drop of water (simulated raindrop) hits the
flour. For younger kids, you might prompt ideas (will the flour puff up? Will it scatter? How
far do you think some will move?). Review the predictions and the process with the group.
Then, have one student stand, holding the baby bottle or eyedropper at waist height over
the plate, and gently squeeze out ONE drop of water so it falls onto the flour. What
happens? Then, ask the student to hold the bottle or dropper at head height and squeeze
out another drop. How are the results different? Ask the students for their observations
and use the laminated data sheet to record your findings. Did their predictions match the
results? Older students might measure the distance of the spatter from the flour pile for
each attempt and later graph the results. Is waist height and head height going to be the
same for each student? How might that change the results?
Depending on the size of your group, and the time you have, let students take turns
conducting the flour experiment, then place just a spoonful of sand on fresh waxed paper
on a second blue plate. How might the sand react differently from the flour when hit with a
raindrop? Collect predictions and then repeat the process of squeezing a water drop from
waist height and head height onto the soil. Lastly, use the gravel, taking predictions and
repeating the test process. Once the experiments are completed, ask students for their
conclusions about the effects of raindrops falling from the sky on loose soil. Will the rate
and duration of rain impact the results? Will the composition of the soil matter? Rainwater
causes weathering when it hits the surface soil and it carries away soil once it rains
enough for there to be “runoff” from the rain (flooding and river action erodes land).
Start with a spoonful of dry flour, sand, and gravel for each rotation. Please use only a
spoonful of each “soil type” for each test. When finished, please use paper towels to wipe
dry the garbage bag, blue plates, eye dropper, and baby bottle before returning them to
the Center 3 box.
If time permits, review the laminated handouts about water erosion: “Which is stronger:
Rocks or Water?” “Rivers: Water is Powerful” and/or “The Outside Story.”
Center 3 Bin
 Plastic spoon
 Baby bottle, mini
bottles and
eyedroppers
 3 blue plates
 Waxed paper
 Plastic table
cloth
 Containers of
flour, sand, and
gravel
 Laminated
Handouts
 Laminated data
sheet for
observations as
a group
Classroom
 Paper towels
 Water
5
Center 4: Slipping Soil
Objective: To experiment with various landscape designs to limit or control erosion.
Tell students that they will examine the impact of water runoff on top soil and try to come
up with solutions to help reduce the effects of erosion. Prepare the erosion table so it
contains a thin layer of packed sand and forms a slope. Fill the table with sand only to the
shallowest tier. Be sure drain spout is at the bottom. Place plastic hose in empty pail on
floor to drain. (use rags from home to prop up the table and make a slope). The steepest
slope will be at the high end of the table and taper off so the sand stops 10-12 inches from
the lower end of the table. The exposed lower end needs to be clear of sand (it depicts a
clear stream bed). Tell the children that the slope represents a bare hillside on which all
trees have been cut, with a clear stream running at the base of the hill. Briefly summarize
“clear cutting” logging and disruption of vegetation for construction. Show some photos of
landslides from Landslides, Slumps and Creep by Goodwin. Ask for predictions about
what will happen to the bare slope when rainwater runs down it?
Then, slowly sprinkle water from the top of the slope using a watering can. Ask for
observations about what happened to the bare slope and to the stream below it as a result
of the water runoff. Point out the quantity of sediment in the “stream” for later comparison.
What will happen eventually if nothing is done to limit the effects of this erosion? How
would animals be impacted if this were a real slope? Now, explain that students must
develop and put in place a plan to reduce the extent of erosion. Ask them about control
methods they have seen in their neighborhoods or in the mountains. Show photos of
erosion control methods from the books Soil and/or Erosion both by D. Stille. Use the
following sorts of questions to help them formulate their erosion control plan (show them
the materials they have to work with): How can the soil be held in place? What could be
added to absorb the water rather than let it run off into the stream? What might divert the
water flow?
Center 4 Box
 wood twigs,
rocks, twigs,
plastic netting,
sponges,
greenery, etc
 Watering cans
 Pail for drain
 Plastic tablecloth
 Trowels
 Shovels
ELF Storage area
 Erosion table
 Sand in bucket –
wet sand
Classroom
 Water
 Paper Towels
Volunteer
 Old “wash-thedog” type towels
for clean-up
Once students have decided on a plan, let them use the nets, greenery, sponges, fabric,
etc. to implement it. Then, let them test their plan by sprinkling water down the top of the
slope. Ask for observations as the water moves down the slope and comparisons of the
amount of sediment that reaches the “stream” versus the amount that occurred prior to
implementing the plan. At the end, talk about the importance of erosion control on
ecosystems, and discuss matters like the importance of staying on marked hiking trails
rather than cutting across switchbacks, which can contribute to erosion. For each rotation,
build the slope back up and clear space for the stream. Add a thin layer of dry top-sand
(smooth with trowel). When rotations are complete, please dry off all materials before
placing in Center 4 box. Please pour sediment water from pail outside. Empty
erosion table and dry for next use. Replace sand in the bucket (NOT BIN) to dry for
later use.
Centers 5 and 6 involve aspects of weathering. Weathering is the breakdown of rock (break), while erosion is the transport
of the products (take). The two types of weathering are chemical and mechanical (or physical) weathering. Chemical
weathering involves decomposition (acidic rain or groundwater, oxidation, lichen). Mechanical weathering involves physical
forces that fracture rocks (water freezing and thawing in small cracks, growth of mineral crystals in cracks, abrasion from
wind, crashing waves, and prying action of plant roots). Ultimately, weathering processes results in the creation of soil. The
forces of chemical weathering and mechanical weathering often work in combination to break down rocks and form soil.
6
Center 5: Shake, Rattle, and Roll / Frozen Erosion
Objective: To examine the weathering effects of abrasion on rock.
Shake, Rattle, and Roll
This center examines mechanical weathering through the impact of water and abrasion on
rocks. Ask students to fill both lidded containers with pieces of rock to the line marked
ROCK. Next, have them fill both containers with water to the line marked WATER. Screw
both lids on tightly and set aside the container marked DON’T SHAKE. Now, pass around
the container marked SHAKE, and have each child take a turn shaking it at least 20 times.
Keep track of the total number of times it is shaken, with 100 shakes as a minimum. Pour
the water from both containers into separate clear cups and compare the water from the
container that was shaken to the water from the container that was not shaken. Is the
color of the water different? Why? Why are there fine particles floating in the water from
the SHAKE container? Where did they come from? Where might a similar process occur
in nature? Perhaps the “DON’T SHAKE” jar represents a calm lake, while the “SHAKE” jar
represents a river or a beach, where rocks are jostled against each other.
Center 5 Bin
 2 lidded jars: one
marked SHAKE
and one marked
DON’T SHAKE
 Clear cups
 Water pitcher
 Pieces of
sandstone
 River rocks
 Beach glass
 Venn diagrams
and charts of
chemical vs.
physical erosion
 Coffee filters
Let the students pour the contents of the two jars through the filters to compare the
amounts of sediment. If you don’t use coffee filters, you might set the clear cups aside so
the sediment in them can settle during other rotations. At the end of the unit, the
coordinator may wish to use these to point out how the sediment has been deposited in
the bottom of the cups. Empty the wet rocks onto a paper towel between rotations. When
finished, please dry off the rocks and spread on paper towel to dry more before next use.
Next, pass around some smooth river rocks and beach glass from the ocean for the
children to feel and observe. Do you think these pieces were always smooth? How did
they get this way? How did our experiment help us to determine this?
Frozen Erosion
FROZEN EROSION
Center 5 Bin
 Scratch rock
 Gloves
 Books: Glaciers
(by George),
Glaciers (by
Brimner),
Glaciers (by
Walker)
Spread an old towel on a table. Let each student use an ice cube with gravel imbedded as
a ‘glacier’ to scrape the scratch rock (moving one direction). Please use one ice cube per
Volunteer:
student. Ask them to imagine how this scraping might work with huge rocks over ten
 Cooler to keep
thousand years. Look through the books, and show the students pictures of terrain that
ice cubes cold
has been shaped by the passage of glaciers.
 Old towel
Note: Bring a small cooler to keep the ice cold. Remember to bring in ice with
gravel imbedded in it.
 Ice cubes w/
pebbles frozen
inside
Explain that glaciers are nature’s bulldozers and that ice has an adhesive grip, which you
can feel if you touch cold ice with damp hands. Because of this grip, rocks are “plucked”
up by glaciers as they move, and these rocks give glaciers tremendous powers of erosion.
Like a giant file, the flowing rocks and ice grate against the underlying terrain. Large bowlshaped hollows, called cirques, are formed. When two glaciers occupy valleys that lie side
by side, they produce a sharp, jagged ridge called an arête. Glaciers slide along because
their bottom layers may begin to melt, or creep due to friction of adjacent crystal layers.
7
Center 6: The Hole Story
Objective: To learn about caves and discover how they are formed.
The process of forming caves in soluble rock is very slow. It begins with rain water falling
through the air and picking up carbon dioxide. Then, as the rain water soaks into the soil,
it picks up more carbon dioxide that is being given off by the decaying vegetation in the
soil. The combination of water and carbon dioxide forms carbonic acid, which is similar to
the fizz in a coke. Over thousands of years as the carbonic acid seeps through the cracks
and crevices of soluble rock (such as limestone, dolomite, gypsum or marble), cavities and
channels are formed creating underground rooms and chambers.
When carbonic acid seeps through limestone, it absorbs the calcium carbonate out of the
limestone (remind students of the “fizz” test with vinegar that they performed on limestone
rocks during the “Rocks & Minerals” unit). This dissolved mineral is dripped into the cave
where the carbon dioxide is then released. Without the carbon dioxide, the water can no
longer carry the minerals, so they are deposited as tiny crystals.
Sometimes calcite (or another soluble mineral) is deposited as the drips hang from the
ceiling of the cave, forming a stalactite. As they drop to the cave floor, they deposit more
minerals and build up stalagmites. Beads of moisture sometimes deposit minerals on the
cave walls in rough-looking clusters called cave coral. Alternatively, water flowing slowly
down the walls or across an incline in the cave form smooth-looking formations known as
flowstone. Mineral formations can take many different shapes, depending on the way the
water comes into the cave.
Guide the students to make a model of a cave being formed: (students could work in pairs
or as individuals)
1.
2.
3.
4.
Place 12 sugar cubes close together on a tray, forming a rectangle (4 x 3
cubes). [one layer of sugar cubes seems to work better than stacking
them]
Make a pancake out of clay that is larger than the sugar cube rectangle.
Place the clay over the cubes and press down the 2 side edges so that
they attach to the plastic plate. Leave the front and back open for water
flow.
Place the tray into a tub resting on the edge so that it is tilted. Slowly
squeeze a baby bottle of water in a stream that runs into the sugar cube
‘rock’. (use about 1/3 of a bottle per cave) After a few minutes, check to
see if the ‘rock’ is being eroded, and if a cave is being formed. Use a
flashlight to explore inside.
If all the ‘rock’ has dissolved, try again with a little less water. If very little
‘rock’ has dissolved, try again with a little more water.
Think about what might happen if there were rock that was very hard to dissolve mixed in
with the rock that is easier to dissolve. If we did the experiment again making small cubes
of clay the same size as the sugar cubes, and mixing them among the sugar cubes, what
do you think would happen? Maybe do this with older students, if time permits.
Share some pictures of caves with the students, looking at the formations.
Center 6 Bin
 Sugar cubes
 Plastic plates
 Modeling clay
 Flashlights
 Baby bottles
 Measuring cup
 Books: Cave by
Knapp; Caves
by Brimner;
Caves by
Walker
Classroom
 Water
 Paper towels
CleanUp is
monumentally
important with
this center.
Rinse the
sugar off the
clay and pat
dry with paper
towels.
Let us know if
you are
running low
on supplies:
MitchellELF@
gmail.com
8
Wrap-up
Options




Slide Show: If you opted for puppet show only for your opening, use the slide show
as a visually powerful closing.
Sharing Circle: Have the kids sit on the floor, forming a circle. Let them pass around
the SHAKE jar or scratch rock from Center 5 (or some other erosion symbol) and pass
it along, as each student who holds it completes the sentence: “Something interesting
about erosion is ______” or “I learned that erosion _______.”
Read a Book: Earthsteps, A Rock’s Journey through Time by Spickert, Erosion by
Rutten, or The Sun, the Wind, and the Rain by Peters.
Erosion Snack Anyone? – Some kind of cookie or brownie covered loosely with
powered or granulated sugar, which the kids could use their straws to blow off (wind
erode) before eating?
Please keep an
eye on the
“drying” sand bin
in the ELF
closet. Stir often
to facilitate
drying – if you’re
there for lunch, a
doc appt., or
otherwise,
go give the sand
a stir!!
Books
In addition to those books listed above for use with specific centers, the following books are available:
Earthsteps, A Rock’s Journey through Time (Spickert)
Erosion (Riley)
Learning About Rocks, Weathering, and Erosion with Graphic Organizers (Estigarribia)
The Sun, the Wind, and the Rain (Peters)
Valleys and Canyons (Brimner)
Materials
For your classroom session, you may need:
1. Puppet stage
2. Intro/Conclusion bin
3. Center 1 bin
4. Drying Sand bin
5. Center 2 bin
6. Center 3 bin
7. Center 4 bin
8. Erosion table
9. Center 5 bin
10. Center 6 bin
You will need the center boxes for only those centers that your class will conduct.
THE THREE KEYS TO THIS UNIT ARE TOWELS, TARPS, AND
TAKING CARE TO LEAVE MATERIALS IN GOOD CONDITION FOR THE NEXT CLASS.
HAVE FUN!