How Can Water Change the Shape of the Land?

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Objective

SWBAT observe and take notes on how water changes the land.

Big Idea

Water is one of the major sources of change in our land. But how does this process work? Let's investigate!

Teacher Notes

Activity Description

The children experience water erosion in a hands-on investigation.  Each partner group makes a sand tower and then observes it eroding as they drop water on the top of it.  They take scientific notes on the process.  To explain the erosion process they watch a short movie and then explain to their partner about erosion.  

NGSS/Common Core Connections

In the NGSS the children are expected to provide evidence that Earth events can occur quickly or slowly.  In order to understand these events and the speed at which they occur, students must understand the processes themselves.  In this activity, they will be representing water erosion, which can be either a slow or a quick process.  While doing this investigation, they will be manipulating sand with water, which will help them to understand models.  In addition, another NGSS standard is for the children to know that both wind and water can shape the land.  

Materials

    • tub of sand (each partner group needs only a vial-full, so you don't need much)
    • vials (you could use any small container as an alternative, such as a film canister)--1 per partner group
    • magnifying glasses--at least one per partner group
    • access to water or a pitcher of water
    • eye dropper (as an alternative you could punch holes in the bottom of a cup; the idea is that you want something that will allow the water to flow gently)--1 per partner group
    • plastic container/bin--1 per partner group; this will be used for each partner group to put their sand in
    • Erosion Water and Sand recording sheet--1 per student
    • Erosion book by Koontz or an alternative book explaining erosion
    • lollipops--1 per student; optional, but it adds an element of fun!

Advanced prep

In advance, I moisten the sand slightly.  I moisten it enough that it turns a darker color and is the consistency that you need when you are making a sand castle.  This will make it keep its form when the kids gently turn the vial over.  You might also to consider preparing your vials of sand for each group, too.  In this way, they can just come up and grab a vial to save time.

Engage!

5 minutes

Water erosion is one of the main causes of change in our land.  But it is something that can be difficult for children to understand.  So in this lesson, we will be doing an investigation so they can actually see how water can erode the land.  At the beginning of the lesson I want them to explore the concept that water can move land.  Since I want the children to discover the process behind erosion on their own, they will do their own investigation with water and sand.

Today we are going to be doing an investigation.  We are going to be investigating the effect that water has on sand.  The question I would like you to focus on is,  "What does water do to the land (or in this case sand)?"  What do you predict might happen?

The questions help focus the children's direction on the investigation to come without being to specific or guiding.  Remember, I want the children to "discover" these ideas on their own.  Making a prediction about what might happen helps them understand that scientific investigations start with questions that are answered by investigation.

Explore

25 minutes

I divide the students into partner groups.  I have them go into their My Clock Buddies for this activity (make sure to read both pages).  Click here for a demonstration on how we use this system to get into partner groups quickly and efficiently.

The partners will each have a turn at gathering materials.  I have the partners decide who is going to get the first set of supplies and who will gather the second set.  I divide the material gathering into two parts since water is involved, and I don't want the children to spill it while doing the first part of the exploration.

I have the first material collector come and get a vial of sand, a plastic bin, a hand lens and an Erosion Water and Sand recording sheet.  I demonstrate how to use the sand to make a sand stack.

For this exploration, I want you to take your vial and gently press your thumb down into the vial.   This will pack the sand into the vial so it will keep it's shape a little bit.  Then gently dump your vial of sand into the box.  You might have to tap the vial at the bottom to coax the sand out, just like when you are making a sand castle at the beach.

You should have a stack of sand.  If your sand falls down, that is OK too.  Either way will work for this activity.  Then I want you to look carefully at your sand.  What could you use to see the sand closer up? What could we use to gather quantitative data?  How do you think a scientist would record their observations?

I want the children to vocalize the idea that a scientist would record their observations by drawing a diagram and also write their observations in words.  They would also measure quantitative data by measuring the tower.  They have space to do both of these things on their paper.  

As they are working, I walk around to make sure they are staying on task and observing carefully.  I check to see that they are working on both their drawings and their writing (see video clip).  The children look like real scientists when they are observing their sand.  They took this job very seriously! 

After the children have had time to record this information, we move on to part 2 and 3.  The second material person needs to get water and an eyedropper for the group.  I have them bring back their vials (and lids) that used to have sand in them so I can fill them with water.  I have a sink in the room, so as they come up I quickly rinse any remaining sand out and fill the vial back up.  I put the lid on so it doesn't spill on the way back. 

 Now I would like you to suck up water in the dropper and drop 40 drops of water on your sand.  Hold the water up away from the sand when you are dropping it.  To be accurate, make sure you counting your drops aloud.  Observe what is happening and write it down.  Draw a diagram of what you observe.  Then you need repeat the process by dropping another 40 drops on the sand.  

Adding the drops with the eyedropper keeps the process of change at a slow and steady pace.  Forty drops will create a change that is noticeable, but not too damaging.  I do not specify how the drops are added to the sand.  So it is funny that some children purposely add the drops in the exact spot and how other space it out.  I think either way is fine and this will create a talking point later on in our discussions.

As the children are working, I walk around to make sure they are following the procedures.  I also stop and ask them about their observations and what they noticed.  I want to see that they are making the connection that the water is moving the sand in some way (see water shrinking video clip).  

At this point, I do not give them too much information or guide them since I want them to discover the basic idea of erosion on their own.  Experiencing the main concept of erosion on their own will later help them understand the erosion process later when it is explained.   It is important for the children to realize that the world can be discovered through their own investigations.  By constructing their own meaning of the activity helps lead them to an understanding that they will remember.

Explanation

20 minutes

 I call the children in the corner so I can read the book Erosion by Koontz.  The book mostly is devoted to water erosion.  It is a great book which teaches the children about erosion at their level.  But before I start reading the book, I give the children a lollipop without any further explanation.  They just think that I am giving them a lollipop since they are great scientists.  The real reason I am giving them the lollipop is because Billy Blue Hair, a character in the video we are going to watch,  uses a lollipop to show the children about erosion.  I give it to them before I read since that gives them time for their candy to start "eroding" in their mouth by the time we are ready to watch Billy Blue Hair.  

As we are reading, we stop and discuss the book and the pictures.  Then we watch a Billy Blue Hair episode called What is Erosion?  It is fun to see their reaction when they realize the real reason I gave them the lollipop.  This starts a great discussion about erosion and how it is like licking a sucker.  The video itself is short and sweet.  It gets the main points of water erosion across in a way that is entertaining to the children.

Elaboration

10 minutes

To elaborate on the ideas learned, we do a classroom investigation.  I want them to be able to take the ideas about erosion that we have just learned about and apply them to a new similar situation.  This time I have one large plastic tub, a Cool-Whip container, sand and water.  I have the students gather around on the rug.  I fill the container with sand and flip it over in the large tub.

Instead of  making a sand stack, we are going to be investigating what happens to larger landforms using a greater amount of water.  I am going to be slowly dumping this entire container of water on the sand.  What are your predictions?  What do you think will happen?  Why do you think this way?

Then I gently pour the water over the sand mound.  We watch as the water starts to carve through the sand.  I try to keep the area where I pour the water in a sort of line, so it simulates a river being formed.  

What do you see happening?  What do you think this is like in nature?  Think about the water and landforms that we have learned about.  Does this remind you of any of them?

I want the children to relate the idea that this looks similar to river being carved in land.  Being able to visually see this process and then vocalize it helps them to understand how water can change the land.  

Then I have them watch an interesting video that shows a coastline eroding over the course of a year.  This particular coastline is known for its quick erosion so it makes the perfect subject for a study on erosion.  The camera man took a photo everyday for one year in the same spot.  He set up different colored flags to show the progression of the erosion.  The video itself was shot in 2005, so the quality is not the greatest, but the content of the 2.5 minutes wordless video is definitely worth watching.

We are going to watch a short video that shows a coast that changes over time because of erosion.  In order to make this video, a man set up his video camera and took a picture a day for a year. How many photos would that be?  Then he took the photos and combined them together into a video.  Knowing what you know about water erosion, what do you predict will happen to the coastline over the course of 365 days?  Why do you think you will see change?  What kind of changes will there be?

We watch the video.  The children are very interested so I use that interest to talk further about erosion.

 

 

Wrap-Up

5 minutes

To wrap-up the lesson, we review and discuss what we have observed and learned.  I ask the following questions:

    • What is erosion?
    • How did our investigation show erosion?
    • What happened to the sand when water was dropped on it?
    • Do you think erosion is a slow or a quick change?  Do you think it can be both?  Explain your reasoning.

I also tell them what we will be doing next so they can see how their note taking was an important part of the process.

The notes that you have taken today are an important part of the scientific process.  Scientists gather notes and make observations so they can analyze and interpret their meaning.  This helps them to understand our natural world.  Tomorrow you will be using your notes that you have taken today to write a paragraph about how glaciers change the land.  I can't wait to see your scientific writing.