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Lesson Plan

Earth's Layers

Florissant Fossil Beds National Monument

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Grade Level:

Upper Elementary: Third Grade through Fifth Grade

Subject:

Science

Lesson Duration:

30 Minutes

State Standards:

Colorado Academic Standards for Science: 4th Grade
3.1.d – Develop a scientific explanation for relationships of the components of the solar system.

Thinking Skills:

Understanding: Understand the main idea of material heard, viewed, or read. Interpret or summarize the ideas in own words.

Essential Question

What does the inside of the Earth look like and why?

Objective

Students will be able to list and identify the different layers that make up the Earth and how gravity plays a role in the formation of the planet.

Background

Our planet Earth is composed of several layers. Each layer has a unique density (density = mass/volume). Scientists believe that all planets formed on the basis of gravity. Therefore, the layering of Earth is a result of gravitational pull. The densest layer (inner core) is at the center and the least dense layer (crust) is the outermost layer. The atmosphere, composed of gases, can technically be considered a layer as well and is obviously lighter than the crust.

But why are planets’ layers spherical in shape? Gravity works most efficiently on other particles when pulling in all directions possible, such as a sphere. Because gravity originates at the center of an object and pulls other particles towards it, the particles try to get as close as possible to the center of gravity. However, density determines which particles will be closer and which will be furthest from the center. This results in the layering of Earth and other planets, with the densest layers closest to the center.

Preparation

You will need:

• 5 colors of play dough (yellow, orange, red, green, blue, and optional white)

• A paper plate

• A plastic knife or popsicle stick

• A clear plastic straw (best to use a thick straw to avoid bending)

• Diagram of the Earth's layers (included)

Materials

A diagram showing an inside look at the layers of planet Earth made by NASA.

Download Earth Layers Diagram

Lesson Hook/Preview

The Earth is like an onion; it has layers! This activity will show you what the inside of the Earth looks like.

Procedure

#1: Roll a small ball (about the size of a gumball) of each color of play dough. The yellow ball can be slightly smaller than the rest. If you want to make clouds you will only need a little bit of white and don't need to roll it like the rest.
#2: Take the ball of yellow play dough and set it in the center of your paper plate.
This is the first layer called the inner core. Each layer has a unique density (density=mass/volume). The density will decrease with each layer as we move outward from the inner core. This is due to gravity. The denser something is, the more gravity will pull on it. So the densest materials are pulled closer to the very center of the Earth while less dense layers settle further away from the center.The inner core is at the center of the Earth because it is the densest, made of solid iron and nickel.
#3: Take the ball of orange play dough and flatten it into a rough circle. Once it is flat, wrap it around the yellow ball and cover it completely. The whole ball should look like it is orange with no yellow showing.
This new layer is the outer core. The outer core is made of liquid iron that is slightly less dense than the solid inner core. This is why it rests over the inner core, but is is still denser that the next layer.

#4: Flatten the red ball and wrap it around the orange like you did in step three. Make sure there is no orange showing now.

This is the mantle. This layer is made up of molten rock called magma. When the molten rock is erupted onto the surface it is then called lava.

#5: Flatten the green ball and cover the red with it.

This is the crust. The Earth's crust is made of solid rock that floats on top of the magma in the mantle similar to how ice floats in water. The continents are part of the crust.

#6: Flatten the blue ball and wrap it around the green.

This color represents the atmosphere, which is made of gasses making it the least dense and outermost layer that makes up the Earth.

#7: If you'd like to, you can put extra bits of green to represent the continents that would show through the atmosphere. You can also use bits of the white play dough to make clouds too.

#8: Put your play dough model of Earth on the paper plate. Use the plastic knife to carefully cut the play dough ball in half and look at the inside of it. You should see the different layers of color.

This is what a cross section of the planet Earth would look like. Can you make comparisons between your model of Earth and the diagram?

#9: Lay one half of the model on the plate with the flat part down. Take the straw and push it through the center. Pull the straw through so you can look at it. There should be play dough stuck inside the straw.

You are looking at a “core” sample of what the Earth looks like. Geologists will take core samples to look at rocks that they can’t see on the surface.

Vocabulary

• Density: noun; the mass of a substance per unit volume (Density= mass/volume)

• Gravity: noun; the gravitational attraction of the mass of a heavenly body (such as Earth) for bodies at or near its surface

• Geologist: noun; a person who studies the history of the Earth and its life as recorded in rocks

• Magma: noun; molten rock material within the earth

• Lava: noun; melted rock coming from a volcano

Assessment Materials

Reflection

Look at the half of your model Earth you didn't take a core sample from. Can you name each layer? Compare your core sample to what you see in the cross section. 

Additional Resources

Check out our other Earth's Layers webpage for step by step instructions with pictures!

Contact Information

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