Layers of the earth

Teaching Pre K-8, Apr 2001 by Cowens, John

In this intro to geology, students recreate the Earth's formation.

About eight years ago, I met Laura Wilson, a teacher from Hammon, OK, at an astronomy workshop that I had been asked to attend. She was on our science team and introduced to me the "Layers of the Earth" idea that I have used as a basis for the following lesson. This introductory lesson in earth science will familiarize your students with the layers of the earth and the basic composition and distance of each. It can also be expanded to cover lessons on volcanoes, earthquakes and archaeology.

The main purpose of the lesson is to introduce your students to geology in its simplest form and to show them how a rock is formed.

Student objectives

As a result of these activities your students should be able to:

* Identify the layers of the Earth as well as the approximate distances for each.

1. Crust: 640 miles

2. Mantle: 1,800 miles

3. Outer core: 1,375 miles

4. Inner core: 1,750 miles

Identify and list the sciences that study the Earth's layers and the importance of the information that is gathered from earth science and how it is used.

* Identify the basic composition of each layer.

* Be able to web any subject in groups or individually.

Resources and materials

Teacher materials should include blue, brown, yellow, black and white construction paper. Students will use the paper to mark the appropriate diameter circle that will represent each layer of the earth. Be sure that when you teach this lesson, you also have on hand an apple, a knife and the book The Magic School Bus Inside the Earth by Joanna Cole (Scholastic, 1989).

Each student should have scissors, glue, a black crayon and a white crayon to label with as well as a box of crayons.

Procedure

1 Introduce the layers of the earth to your students by using an apple. Cut the apple exactly in half across the core. Explain that the skin of the apple represents the crust, the heart represents the mantle, the seed coat represents the outer core and the seed represents the inner core.

2 Read The Magic School Bus Inside the Earth to your class. Begin a discussion with your students on how they think that the book explains the layers of the earth and the composition of each.

3 As a group, brainstorm about one or all of the sciences that study the layers of the earth and the importance of each in contributing to our understanding of our earth. Encourage your students to supply either very general or specific information to this discussion.

4 Using the colored construction paper, have each student model the layers of the earth. With the blue sheet, students should measure an 8 112" circle for the crust and label it 6-40 miles. The crust is made of many plates which "float" above mantle. The crust is thicker and lighter at the continents and thinner and denser at the ocean floor.

The brown sheet of construction paper should be used to measure a 7" circle for the mantle and labeled 1,800 miles. The mantle lies below the crust and is a thick layer of solid rock. Many scientists believe that the mantle transfers heat from the core to the surface.

With the yellow sheet, ask students to measure a 6" circle and label it 1,375 miles. This represents the outer core which is made of melted iron and nickel. It is much denser than the rock layers above it. The temperature of the outer core can range from 4000 to 9000 deg F.

Use the black construction paper to represent the inner core. Students should measure a 3" diameter circle and label it 1, 750 miles. The inner core is made of solid iron and nickel. These materials sank to the center of the earth while it was still in molten form.

Have students use the white piece of construction paper as the background and label each of their layers at the top using their black or white crayons as they glue them on to the background. Students should then decorate their projects using their understanding of each layer of the earth. For additional information and interesting facts about the earth's layers to use when teaching this lesson, check out the June/July 1991 edition of The Mailbox Magazine.

Tying it all together

1 Review the importance of studying layers and begin in-depth units on any of the following areas: volcanoes, earthquakes and archaeology.

2 Ask your students to share their projects with the class and explain the differences between each layer.

3 Have the students web as a group or individually the one area of science that uses the layers of the earth that interested them the most.

John Cowens teaches science at Fleming Middle School, Grants Pass, OR, and is a Teaching Editor of Teaching K-8. E-mail: snewoc@yahoo.com