GRADE:

CONTENT STANDARDS: Earth and Space Science

CONTENT TOPIC: Structure Of The Earth

CONCEPT: The constantly changing nature of the earth is evident.

CONTENT OBJECTIVE: 8I1.00 To understand the structure and composition of the earth

INSTRUCTIONAL OBJECTIVES: The learner will:

1.01 describe three layers of the earth.
1.02 construct an earth model.

I. The Earth is made up of three layers
A. Crust
B. Mantle
C. Core
II. Volume, mass and density varies with each layer

TN COMPONENT OF SCIENCE: Unifying Concepts of Science

TN GOAL:

To enable students to acquire scientific knowledge by applying concepts, theories, principles and laws from life/environmental, physical, and earth/space science.

2.1 SCALE AND MODEL - The development of models provides a conceptual bridge between the concrete and the abstract, while the use of scales allows for a comparison of differences in magnitude between the model and the desired form.

2.1a A model is a representation used to simplify complex phenomena.

BENCHMARK: Models are often used to represent concepts of various magnitudes.

2.1c Models are often used to study processes that happen too slowly, too quickly, or on too small or too large a scale to observe directly.

BENCHMARK: Models are often used to represent processes that cannot be directly observed.

2.1d The scale chosen for a model determines its effectiveness.

BENCHMARK: The usefulness of a graph or drawing is determined by the scale utilized.

TIME REQUIRED:

30 minutes

3 different colors of clay, play dough, etc. (any colorful, moldable material will do), Styrofoam balls (15 centimeters)

Core, crust, mantle, plasticity

What does it mean to be "Solid To The Core"? (The earth has a solid core.) (Pass out 3 different colors of clay to each student.)

The earth is made up of three layers. Covering the outside of the earth is a thin, solid layer called the crust. The thickness of the crust differs from place to place. The parts of the crust that make up the sea floor are from 4-7 km thick. Under the continents, the crust is about 35 km thick and beneath some mountains, the crust is as much as 70 km thick. We know more about the crust than any other layer because we can see rock and soil. However, the crust makes up only one percent of the earth's volume. (Have students make their crust.)

Beneath the crust is a very thick layer called the mantle. The mantle reaches to a depth of about 2,900 km beneath the crust. It makes up about 80 percent of the earth's volume and represents almost two-thirds of the earth's mass. (Students now shape their clay "mantle.")

Deep in the earth's center is a very dense core. It is made up of a solid inner core surrounded by a liquid outer core. The core makes up 19 percent of the earth's volume and nearly one-third of its mass. Of all the substances commonly found in the earth, only a mixture of iron and nickel is dense enough to account for the denseness of the core. (Students now make a "core" and place their mantle, then crust to show the 3 major parts of the earth.)

1. Make a model of the Earth's interior.

Obtain a Styrofoam ball 15 centimeters or more in diameter. Carefully cut a wedge out of the ball. Draw lines on the inside of the ball and the wedge to represent the four layers of the earth. Use the diagram of the earth's layers (provided) as a reference. Label and color the layers on the ball and wedge with different colors. (The handout of the four layers of the earth can be duplicated and labeled for further reinforcement of the objective.)

If you could take a slice out of the Earth you would find that it has four layers. Label each of these layers .

2. Simulating Plasticity

Problem: How can the property of plasticity be shown?

Objective: In this activity, students will use a cornstarch-and-water mixture to simulate the plasticity of the earth's mantle.

Materials: Each group of students will need 15 grams of cornstarch, 10 milliliters of water, 2 small beakers, a metal stirring rod or spoon, and an eyedropper.

Procedure:


a. Place the 15 grams of cornstarch into one of the beakers. In the other beaker place 10 milliliters of water. Is the cornstarch a solid, liquid, or gas? The water?

b. Using the eyedropper, gradually add one eyedropper-full of water to the cornstarch. Stir the mixture.

c. Continue adding water, one eyedropper-full at a time. Stir the mixture after each addition. When the mixture becomes difficult to stir, do not add any more water.

d. Try to pour the mixture into your hand. Is the mixture a solid, liquid, or gas?

e. Try to roll the mixture into a ball. Does the mixture act like a solid, liquid, or gas?

f. How is the cornstarch-and-water mixture similar to the Earth's mantle? How is it different?

Answers: Students will be able to observe that cornstarch mixed with water behaves like a solid and a liquid, depending on how much pressure is applied to the mixture. When they squeeze it in their hand or roll it into a ball with consistent pressure, it has the characteristics of a solid. When they release the pressure, the mixture flows like a liquid. The trick to achieving this effect is in adding just the right amount of water to the cornstarch.

During this activity you might want to have the students wear lab jackets to protect their clothes. Water will remove any cornstarch that gets onto clothes or other surfaces.

GENERAL CHARACTERISTICS OF THE LAYERS OF THE EARTH

CHEMICAL MAKEUP

AVERAGE THICKNESS (km)

PERCENTAGE OF TOTAL MASS OF THE EARTH

---

Crust

oxygen, magnesium aluminum, silicon calcium, sodium potassium, iron

35 (continents) 7 (oceans)

0.4

---

Mantle

silicon, oxygen aluminum, iron

2900

68.1

---

Outer Core

iron, nickel (liquid)

2200

31.5

---

Inner Core

iron, nickel (solid)

1270

---

The layers of the earth differ in chemical makeup, thickness, and mass. What element is found in every layer of the earth? (Iron)

Turn to your neighbor and explain your earth model to them, then let your neighbor explain theirs to you .

core - innermost part of the earth

crust - thin outer layer of the earth found under the oceans and continents

mantle - layer beneath the crust; extends to a depth of 2900 kilometers

plasticity - ability of a solid to flow or change shape like a thick liquid

This is the time this file has been accessed since 04/04/98.

The University of Tennessee at Martin is not responsible for the information or views expressed here.

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