Soil Secrets-Earth Erodes!

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Objective

Students demonstrate soil erosion by creating a model and designing a structure to stop erosion!

Big Idea

Why is it important to protect the topsoil?

Hook

5 minutes

I rang my chime to get the class’s attention.  I announced that we were about to begin the fifth Science lesson in our unit about soil.  I asked them to return to the carpet squares and ‘Show Five’.  Once seated, I asked them, “How many of you remember our first soil lesson, when we just started to explore soil?”  I waited for answers from the class as a few students raise their hands.  “Now how many of you remember squeezing pieces of dirt and watching them crumble?”  More students now raise their hands (I knew that reminding them about playing with dirt would get their attention!) “Let me read you a book and tell you more about this process.”  As simple as it is, this quick act give the students a quick connection to the lesson.

Whole Group Instruction

10 minutes

I read Erosion by Cherie Winner (although the book is out of print, it’s readily available on Amazon.  And if you use Amazon Smile, it’s an effortless fundraiser for your school!).  The book itself is written at a level above our students, so as I read, I liberally edit to target key points. I stop to introduce and highlight a few concepts about the appearance of the soil, “We are going to study about soil erosion today.  Practice that word with me.  E..ros..ion.”.  I practice new vocabulary to give the students an opportunity to absorb new terms and give it context while I read the book.  “Erosion comes from a Latin word that means ‘to slowly eat away’."

"Lots of things can eat away at the ground.  Can you think of any?”  “Rain?”  “Big trucks?”  “Both of those are good answers.  People do have a part in the eroding of the Earth.  Can you think of any examples with nature?”  "When it rains, there are holes in the ground."  Right, nature also plays a part, just by the way it effects the earth.  A lot of the time, nature's part in erosion is through water- rain, rivers, and ice."  I hold up a diagram that details some of these forms of erosion.  "The water finds a crack and works it’s way in."  I hold up a picture of the Grand Canyon to illustrate, as I point out the pattern that shows this erosion. "What could cause this land formation?"  When I got puzzled looks, I explained..."A crack got bigger until it becomes something like the.."  "Grand Canyon!”   "What?!?!"   "Water is a wonderful- and powerful- force of nature!" 

Wind is another form of nature that contributes to erosion".  To illustrate this, I hold up one of the pictures in the book that gives a perspective on the effects of wind on the land.  “Knowing what we learned about weather, what can strong winds do to the land?"    "It moves it?"  "Yep, strong winds can push soil from one place to another, moving it long distances.  Wind and water work together to create the shape of our Earth today.  Who can help me create a strong wind?”  We take a minute to make a collective breath and blow together.  This gives a brief instruction break, as well re-connecting them to the lesson.  

 

Small Group Instruction

15 minutes

Materials:

• Soil Samples (2-3 cups per group should be enough)

• Water and container

• Simple building materials (e.g. toothpicks, small twigs)

When they're seated, I continue,  “Today, we get to be “Geologists”.  These are people who study the Earth’s formations and find ways to protect them.  We’re going to find some ways that we can help our formations stay the same, even when there’s water and wind around it.”  “But why do we want to do that?”  “Great question!  Because sometimes, geologists need to create a way for the topsoil  to stay in the same place so it can support the life around it.  Topsoil is an important type of soil because it does a big job to help plants grow.  If all the topsoil goes away, what’s left?”  "No plants!"  "So what could we build?  Take a minute a turn to your partner to share two things."  I wait about thirty seconds before I use the chime to dismiss the students by tables.

As they arrive, I review some instructions:

• First, use the dirt on our table to create a structure or formation. Anything that stands up is fine.

• Next, use some small bottles to pour water on it and observe the eroding effect on the formation.

• Last, work like geologists to create some support to help stop the erosion.  Use the toothpicks on your table if you want to.

Examining and testing are important steps of Science examinations, so I always work to include this in lessons when applicable.  The engineering piece is an interesting part of the lesson because it forces the students to communicate, implement, test, adjust, and finalize their ideas.  All these things loom large in their future education and careers, regardless of the area of specialty.  I mingle among them and listen to their conversations, helping them clarify what they are observing and adjust their structures when necessary.  I notice that some students need the demo before they fully understand the concept of erosion.  After ten minutes or so, things begin to wind down and I ring the chime to give a one-minute warning.  “When you’re finished, go ahead and leave the structures on your table and come back to your carpet squares.”

Wrap Up

5 minutes

After everyone washes their hands, I ask them to head back to their carpet squares.  I ask the students to discuss what helped their structure stay together, even after water was poured on it. “We put toothpicks around it so the dirt didn’t wash away.”  “We pressed it down hard so it stayed in one place.”  "I put popsicle sticks down so the soil wouldn't move."  "How does this knowledge help us in our real life?"  "Then we know how to plant things so they can grow."  "Right!  Like we said, nature is helpful..as long as we help it be that way."  After all ideas were shared, we display the examples near the Science area so the students could refer to them during future Science lessons.