# How Can the Layers of the Earth be Modeled?

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## Objective

SWBAT explain how one can use a model to represent an object.

#### Big Idea

In this lesson, the children will learn about the layers of the Earth and explain how models can be used. Then they will compare two different models.

## Teacher Notes

Activity Description

Watch the short video for an activity description and to preview the resources.

The lesson begins by having the children explore and discuss how one could make models of the layers of the Earth.  Then the teacher creates a clay model of the Earth while explaining each of the layers.  Then they will discuss how the two models are alike and different.

NGSS/Common Core Connections

By the end of this unit, called Earth Changes, the children will have to understand how the movement of the crust and mantle creates changes, either quickly or slowly.  Thus the children need some background on the layers to help them understand how these events happen.  Also, as a science practice and part of the NGSS, the children are expected to understand and develop models.  In this lesson the children will be comparing two different types of models, diagrams and a physical replica.

Materials

photo of supplies

## Engage!

5 minutes

I engage the students by asking giving them a topic to explore with their Turn and Talk Partners.

We are going to be learning about the Earth today.  I bet some of you know something about the Earth.  I would like you to discuss what you know with your turn and talk partner.

Using turn and talk partners is a strategy that I often use when I want the children to have a short discussion. Their partner is the person who is sitting the closest to them.  I use this when we are having a quick discussion and I need them to get with a partner quickly.

Having the children explain to someone what they know about the Earth gets them thinking about the topic of today's lesson.  Plus it gives me a chance to pre-assess the children's knowledge.  In this way, I can cater my teaching according to their responses.  I am expecting that the children will be talking about the outer layer of the Earth, since most of them are unaware of the layers inside. But if I notice that they know more than I have expected, I can change my lesson accordingly.

In this video clip you will see Turn and Talk partners in action.  It might sound really noisy in the room, but actually I was very proud of my rambunctious group for staying right on task and discussing the prompt.  The boy in the clip was knowledgeable about the Earth, since he had just watched a movie about it.  He was very proud to share his ideas.  I love the interaction between the two.  Notice how the girl uses her Partner Power sheet to help her communicate effectively.

## Explore

10 minutes

I show the students the first 4 minutes of a 6 minute video about the core and other layers of the Earth.  It is informational, and gets them interested in the topic.  Of course, at this point, they won't understand all that is happening, but it whets their educational appetite.  You could stop the video after about 4 minutes and they will still get the main idea that the Earth has different layers and those layers can be modeled.  I love in the video how they modeled the layers by using a layered cake.

Did you know that the Earth has layers?  We are going to be learning about the layers of the Earth.  We are going to be using a model in order to understand the layers better.  Knowing what you already know about models, how could we model the Earth and its layers?

I would like you to write the answer to that question in your science journal.

I write a sentence starter on the board.

I think people can model the layers of the Earth by......

I want the children to complete the sentence with their thoughts.  They should add details to explain their thoughts.  Click here for a student sample.  If they would like, they can also draw a picture to complement their idea.  Here is a video clip of some girls sharing their ideas of modeling the layers of the Earth with different colored sand.

## Explanation

15 minutes

As part of the NGSS, the children need to be able to provide evidence that Earth's changes can occur slowly or quickly.  In order to do that, they must have a basic understanding of the cause of those changes.  Thus they need some understanding of plate tectonics, but this can be difficult. It is really hard for them to visualize something that they are not able to observe.  To help the children understand simple plate tectonics, they first need some knowledge of the Earth's layers.  During this part of the lesson the children will observe me making a simple model about the layers of the Earth.

(Note:  The children will have a chance to make their own edible model later in this lesson).

Do you remember when we were building our landform models?  What is a model?  Why do scientists use models?  How does a model relate to the real object?

My goal is to have them relate a past common learning experience to what we are going to learn about.  This connection will help them better understand the abstract of plate tectonics.  The concept of the structure of the Earth itself hard for the children to grasp, yet alone the idea that the Earth is always changing.  But if I use a model to show them, and they understand what a model is from past experience, they are more likely to understand the concept.

I make sure that I have all of my materials ready (as noted in the teacher section).  To make it a tad easier, I have rolled out some of the dough, like the blue and red, since they are large Earth layers and need to cover a large span.  I also have pre-made a few green "continents" so I don't have to take our precious time making them later.

First I begin my model by holding up the marble for all of the children to observe.

What can you tell me about marbles?  What type of characteristics do they have?

I want the children to come up with the idea that marbles are hard and their shape stays the same.  Coming up with these ideas on their own makes the learning more relevant to them.  I refer to this explanation sheet as a reference when I am explaining each layer.

This marble is going to represent the center of the Earth.  The center of the Earth is called the "inner core."  It is solid like a marble because it is under a lot of pressure.  In our Earth model, it will be in the center.  I am going to cover the marble with yellow clay. Right now,  we cannot put the marble in the middle of the model of Earth until we are done since we will be cutting through the Earth and I cannot cut through a marble.

Next I roll orange clay into a ball about 3 inches in diameter.

The orange clay represents the outer core.  Most of the rock in the outer core is so hot that it is molten, or liquid rock.  It is 2250 km thick.

Next I wrap red clay around the outer core.  Since it is actually the thickest layer, I make sure it is represented accurately.

The red clay represents the Earth's mantle.  It is the thickest layer of Earth.  It is mostly solid rock.  Some of the rock flows slowly like an extremely thick liquid.  It is 2900 km thick. In this unit, called Earth Changes, we are going to be studying about earthquakes, volcanoes, and mountain formation.  The slow movement of the mantle can cause  each of these events.

I wrap a thin layer of blue clay for the crust, since it is only 5 km to 64 km thick.

The blue part is called the crust.  The crust is the outer layer of the Earth.  This thin layer covers our Earth.  This layer is covered with soil, rock and water.  In some parts it is only 5 km thick.  In other parts it is 64 km thick.  The crust is thinnest under the oceans and thickest under the continents.

Next I tell the children I am going to cut the model in half.  They gasp and giggle with excitement!  Then I slice our Earth model in half by using wire so the children can see the layers (see photo of Earth model inner layers and outside).  They actually clap when I show them the inside layers.  How fun is that?  I don't know about you, but I don't often have applause for lessons.  It definitely was a highlight of my day and theirs.

Using this model helps them understand how thick the layers are.  It also helps them understand the concept that the Earth is not just a ball, it has layers.  Understanding that the Earth has layers will help them later understand earth changes, such as mountain formation, earthquakes and volcanoes.

As we look at the layers of our clay model, we review names of the layers and the information that they have learned.  I want the children to understand that each of these layers are part of the Earth, just as is modeled.  These individual parts are work together to make a whole.

## Evaluation

15 minutes

I then pull up the Layers of the Earth diagram teaching poster.

How is our model is like this diagram?  How is it different?

Understanding that scientists can use different models to depict the same object is an important idea.  As part of the science practices, the children are expected to compare models to identify common features and differences.

Since explaining their thoughts about models can be tricky, we discuss the differences orally as a class. It can help the children who struggle with concepts or the language (see video clip of our discussion). Then I have the children answer the two questions in their science notebooks.

In their answer, I am looking for them to state at least one difference and at least one similarity.