Water Changes The Shape of The Land

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SWBAT use a model to witness the effects of erosion

Big Idea

Water carries away part of the land as it travels down hill. We can model this in the classroom.

Background Information

In a previous lesson students created a model of landforms. They will use that model to see the effects of water in causing erosion. 

The Next Generation Science Standard ESS2A states that students should understand that wind and water change the shape of the land. This lesson is designed to help students visualize this by seeing how the water moves down a mountain taking dirt and rocks with it. 

I want students to develop a conceptual model of how water can change the shape of the land and so I am creating a hands on lesson where students can be actively engaged in the process of witnessing erosion. 

Getting Ready

15 minutes

I bring out the clay models that students made in a previous lesson. I choose the models that are of mountains and hills. I say, "What would happen if it rained and water ran down the mountain?" 

I listen to the student responses then say, "I think those are good estimations of what might happen. Now I have another question for you. What is the surface of a mountain covered with?" (rocks, dirt, grass). "What happens to those things when the water runs over them?" (nothing, they move, they get wet). "Ok, well today we are going to see what really does happen because you have made some really good suggestions about what might happen."

Let's read our I Can statement together. We read, "I can figure out what happens when water runs down a mountain."

"Would you take out your science journals and put today's date at the top of the page. Now I would like you to make a prediction about what will happen when the water runs down the mountain over the dirt, grass and rocks." I hand out the journal page for students to record their predictions. Predicting is an important part of the scientific process that students should be learning so I give them time to think and predict before we do the experiment. water changes journal page.pdf 

Using Our Models

20 minutes

We have 6 different landform models that we created in a previous lesson. All but 1 has hills on it so we will use the 5 hilly landforms. In order to protect the clay from the water, and to make it possible to add dirt, small pebbles, etc. to the outside of the clay structures, I cover each one with plastic wrap. I have a bag of dirt and a bag of small pebbles.

I say, "I want you to imagine that you are on the side of one of these hills or mountains. You already told me that they would have rocks, dirt and grass on them. We are going to put the rocks and dirt on the sides of the hills. I have covered each one with plastic wrap and left some folds in the wrap to help you keep the dirt and rocks on the sides of the hills. A real landscape will not be nice and smooth so I want you to do your best to put rocks and dirt over the outside of the models."

I know that this part of the project will keep students actively engaged and interested in engaging with the scientific content. I want students to stay engaged throughout the process so I create each step to encourage participation.

Once the students have added dirt and pebbles to their models I ask, "Where might water come from on a mountain or hill?" (from a river, from rain, from snow). "Ok, we are going to make it rain on our models and I want you to observe what happens to the rocks and dirt on the sides of the mountains. Do they stay in the same place? You will need to watch carefully as you take turns to make it rain. I will give each person a small cup of water to sprinkle on the mountainside .You will pour your water into the watering can and then sprinkle it while your teammates watch." (I demonstrate the difference between pouring and sprinkling.)

I give each person their cup of water and provide each team with a watering can. As students take turns sprinkling the mountains, I circulate around to ask students what they are noticing.


What Did We Notice?

15 minutes

Once everyone has had a turn with the water and observation, I ask students to return to their seats. I ask, "What did you observe when you sprinkled the water on your models? What happened to the dirt and rock?" I let students share their observations.

I expect students to talk about how the rocks and dirt ended up at the bottom of the hill with the water, that the water formed streams as it went down the mountains, that the dirt or rocks didn't end up where they started. This would show an understanding that water changes the shape of the land and would address the NGS Standard 2-ESS2-1a.

"Now I would like you to look back at your journal entry. Did you predict what actually happened? Is it ok if your prediction is not the same as what you saw?" (This is important because so many second graders want to change the prediction to match the outcome so they can say they were right.) 

"Now in your journal I would like you to use words and pictures to describe what you observed." I give students about 5 minutes to complete their Journal Entry and then I invite them to the rug.

Erosion: One of Water's Jobs

10 minutes

"You told me how the rocks and dirt moved when the water ran down your mountains. Do you think that really happens outside?" (Yes, no * see lesson extension for a way to show this outside as well)

"There is a word for when water moves dirt or rocks out of its way. It is erosion. Erosion is what happens when a lot of water or even wind rushes over the land. The land moves just as it did on your models because the water picks up the dirt, and if the water is moving fast enough it even picks up big rocks, or even trees. This is called erosion. It is a new word for many of you and one that you can go home and share with your parents tonight. What you watched today was the process of erosion of the dirt and rocks from the side of the mountains because of the moving water.

Would anyone like to share any final thoughts about what they saw and learned today?" 

We end with student comments about the activity.

Lesson Extension

25 minutes

It is possible to extend this lesson in several ways. After a heavy rainstorm take students outside to any hilly areas in the school yard. Have them look for evidence of where the water has moved rocks, dirt or even leaves from one place to another.

If there have not been any rainstorms, fill a large container with water. Walk to a hillside that is mostly dirt and small rocks. Pour the water over the ground and have the students witness what happens to the dirt and rocks as the water moves over them. Does the water go in a straight line? Does it go around some of the larger rocks? Does it move some of the dirt and leave a path where it has traveled?

These extensions further explain to students how water changes the shape of our land.