1. 6th Grade Earth Science Standards 6E5A. F. G.
Unit 2 Inside the Earth
6th Grade Earth Science
Standards 6E5A. F. G.

2. Eggcellent Earth Phenomena
What is inside an egg?
How do you know what’s inside the egg?
What if you had never seen what was inside an egg?
How would you know what it was made of?
What about the Earth? What’s inside?
We cannot break Earth open, and we cannot drill all the way through. So, how do we gather evidence to determine what’s inside?

3. Seismic waves
During earthquakes, scientists use seismic waves to gather information about what our planet is made of. Waves travel at different speeds as they move through layers of various densities. Indirect evidence leads us to believe that our planet is made of distinct layers, each with its own unique characteristics.

4. Modeling Layers Based on Chemical Composition
Explore Part 1

5. Background Information
Earth can be categorized and divided into layers by understanding what kind of material makes up each layer. The crust of Earth is made mostly of the elements of silicon, oxygen, and aluminum.

6. Crust
There are two types of crust that make up this outermost layer of the Earth. We observe the oceanic crust of Earth when we look underwater at ocean floors and the continental crust when we stand on the ground and look out over the land. The crust is not very thick when compared to the rest of Earth.

7. Activity: Crust
Place plastic wrap inside half an egg mold. Smooth the plastic so it sticks inside the half sphere.
Press yellow clay into the sphere leaving an empty space in the middle. This layer is very thin.
On your graphic organizer, use a yellow color pencil to color the crust in the cross section diagram and the legend.

8. Activity: Mantle
Next, model Earth’s mantle. The mantle is made of silicates that include elements such as iron and magnesium. This makes them denser than crust silicates.
Press the red clay into the space on top of the yellow clay, leaving a space in the middle.
On your graphic organizer, use red to color the mantle in the cross section diagram and the legend.

9. Activity: Core
Finally, model the Earth’s innermost area, the core. The core includes Earth’s densest materials, the elements iron and nickel.
Press the white clay into the center of the model to represent the core.
In your student journal, leave the innermost circle white to represent the core in the cross section diagram and the legend.
Give your model to you teacher and let it dry.

10. Reflection Questions
What is the chemical composition (or make up) of the crust material?
Where is the crust found?
What is the chemical composition (or make up) of most of the Earth’s mantle material?
What is the chemical composition (make up) of Earth’s core?
Which layer makes up the majority of Earth’s interior?
Which layer is the thinnest when looking at a cross section of Earth?

11. Modeling Layers Based on State of Matter
Explore Part II

12. Lithosphere Background
We learned that different materials make up Earth, and the layers of crust, mantle, and core are classified based on their different chemical compositions. We expect to find Earth’s materials in a state of matter, either solid or liquid. However, the interior of Earth holds surprises as we continue to investigate a different way to classify layers of Earth. We don’t sink as we stand on the surface of Earth or even on the bottom of the ocean floor because we stand on cool, solid material. All of the crust is in a solid state of matter. A little bit of the outer part of the mantle is solid, too. This layer, based on its solid state, is called the lithosphere.

13. Lithosphere Take your model out of the mold.
Look at the cross section part of your model. Use a black pen or marker to draw a dotted line all the way around the red mantle, almost on the edge, so that only a little of the red is outside of the circle near the yellow.

14. Lithosphere Continued
Remember, all the yellow as well as a little of the red cool and solid. This cool and solid layer is called the lithosphere and your dotted line is its boundary.
Return to the cross section diagram that you colored. Use the marker to draw in a dotted line on the diagram just as you did on the model.
Use a pencil to draw an arrow to point out and label the lithosphere layer on the cross section diagram.

15. Asthenosphere Background
The layer just below the lithosphere is the asthenosphere. The dotted line on your model represents the boundary that separates the lithosphere and the layer called the asthenosphere. The asthenosphere is classified based on its state of matter; it does not behave like a solid or liquid. The best way to describe the asthenosphere is “a solid that flows.” Let’s see where the asthenosphere is located using the model.

16. Procedure
Look at the red mantle of your model. Find the lithosphere boundary dotted line that you added. Use a black marker to draw in one more dotted line just below the dotted line for the lithosphere boundary. The thin layer between your two dotted boundary lines in the asthenosphere.
Return to the cross section diagram that you colored in Part 1 of your Student Journal. Use the marker to draw in a second dotted line on the diagram so that it matches your model. Remember, the red between these dotted lines is classified as the asthenosphere because the material of this layer behaves as a “solid that flows.”

17. Procedure Continued
Use a pencil to draw an arrow to point out and label the asthenosphere layer on the cross section diagram.
The inner core and the outer core are in different states of matter. Both layers experience extremely high temperatures, but the inner core is solid. Draw a dotted line in the circle within the interior of the white core to show the separation between the outer core, which is in the liquid state of matter, and the inner core, which is in the solid state of matter.

18. Procedure
Add the same dotted line to your cross section, and use a pencil to point out and label the inner and outer cores.
Follow disposal and reuse directions* for materials, and then answer Part II questions in your journal.
*Peel off and throw away the plastic wrap. Return the reusable mold.

19. Student Journal Questions
What are three basic states of matter?
Which of the crust/mantle/core layers are located in the lithosphere?
What is the state of matter of the lithosphere?
Which layer is classified based on chemical composition is found in the asthenosphere?
What is unusual about the asthenosphere’s state of matter?
Look at the model and think about a logical reason why the inner core is under more pressure that the outer core. What causes more pressure in the inner core?
What is the logical reason why the inner core’s state of matter (solid) is different from the outer core’s state of matter (liquid)? Hint: Look at question 6 above.
What characteristic or property of Earth’s material is used to classify layers as lithosphere or asthenosphere, as well as the inner or outer core?

20. Investigating Solids That Flow
Explore Part III

21. Background Information
In the upper part of Earth’s mantle, we find the asthenosphere, which lies directly below the cool and solid lithosphere. The asthenosphere is a solid, but it has plasticity, which allows it to move and flex similar to Silly Putty. Let’s explore what plasticity really means.

22. Procedure
Measure 30g of cornstarch and place it in the plastic bag. Add 25 mL of water.
Zip the bag closed and squeeze the water until it mixes with all parts of the cornstarch so that it is thick and without clumps. You should not be able to see any dry cornstarch in the bag.
Explore this mixture with the bag zipped closed.
Extension: Take out a handful of the mixture and roll it into a small ball. Stop and let the mixture “melt” in your hand. This is how the plasticity of the upper mantle works.
Clean up your materials and work space.
Answer questions for Part III in your student journal.

23. Student Journal Questions
Press down gently on your bag that represents the asthenosphere. When you first press down gently on the bag, what does it feel like?
Now, poke the bag quickly. How does the asthenosphere respond?
The asthenosphere layer is a solid with plasticity. How does this substance act like a solid?
How does the substance act like a liquid?
Think about the asthenosphere’s property of plasticity. How might the plasticity of the asthenosphere affect the layer directly above it, the lithosphere? How do you think the solid lithosphere and the flexible asthenosphere interact?

24. Layers of the Earth
Explain

25. The Crust The crust is the outer most layer of Earth.
Two types of crust
Oceanic crust: under the ocean
3-5 miles thick
Continental crust: land above the ocean
25 miles thick
The crust is made up of tectonic plates (think puzzle pieces).
Tectonic plates will build up pressure as the move and stick together causing earthquakes.

26. The Mantle The mantle is the largest layer directly under the crust.
1,800 miles thick
Very hot dense rock
Moves around like a melted liquid and causes the Earth’s tectonic plates to move.
Convection Currents move the melted liquid

27. The Outer Core Third layer of the earth. Surrounds the inner core.
Creates Earth’s magnetic field.
The magnetic field is the protective barrier around the Earth that shields us from the Sun’s solar winds.

28. The Inner Core Inner most layer, the center of the Earth.
Solid ball of metal
Hottest part on Earth, almost as hot as the Sun.

29. The Lithosphere
The lithosphere contains the crust and the upper part of the mantle.
The lithosphere is broken into tectonic plates that are in constant motion.
The movement of the tectonic plates are what create major geologic events like earthquakes, volcanic eruptions, and mountains.

30. The Asthenosphere
The asthenosphere is just below the lithosphere and change shape without breaking.
The asthenosphere is melted rock that moves due to convection currents.
These convection currents are the reason the tectonic plates in the lithosphere move.

31. The Outer Core Third layer of the earth. Surrounds the inner core.
Creates Earth’s magnetic field.
The magnetic field is the protective barrier around the Earth that shields us from the Sun’s solar winds.

32. The Inner Core Inner most layer, the center of the Earth.
Solid ball of metal
Hottest part on Earth, almost as hot as the Sun.

33. Convection Currents in the Mantle
Convection Current Video
Convection currents in the mantle are created by heat from the core moving to the crust.
Three types of heat transfer
Radiation: the transfer of energy through empoty space; has not direct contact between heat source and an object Example: sunlight
Conduction: heat transfer by direct contact of particles of matter Example: metal spoon heating up in a pot of soup
Convection: transfer of heat by the movement of a heated fluid (includes liquids and gases)

34. Convection Currents in the Mantle
Heat transfer by convection is caused by differences in temperature and density within a fluid.
Density: the measure of how much mass there is in a volume of a substance
Example: heating water on a stove – as water on the bottom gets hot, it expands, becomes less dense and rises; when the surface water starts warming up it becomes denser and moves to the bottom causing a convection current, or the flow that transfers heat.

35. Convection in the Mantle Continued
Convection currents flow in the mantle-heat source is the Earth’s core and from the mantle itself. These currents have been acting like a conveyor belt moving the lithosphere above for the past four billion years.

36. Density and Temperature
Density is what determines how the layers of Earth are positioned.
The inner core is more dense that the other layers because it is an actual solid and has more mass.
The inner core is hotter than the other layers. As the layers progress outwards to the crust, the temperature decreases.