Lesson Plans

Procedures for Using the Science Lesson Plans

Glaciers

Arctic vs. Antarctic

Food Webs

Insulation

Penguins

Cupcake Core Sampling

Wind Chill

Ozone Hole

Plate Tectonics

Plate Tectonics

Objective

Students will identify the three layers of the earth: core, mantle and crust.

Students will demonstrate knowledge of the concepts of convergent and divergent motions of the earth.

Students will define plate tectonics.

Standards Assessed

Earth Science
Grade 8

6-8 Benchmark

E. Describe the processes that contribute to the continuous changing of Earth’s surface (e.g., earthquakes, volcanic eruptions, erosion, mountain building and lithospheric plate movements).

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09. Describe the interior structure of Earth and Earth’s crust as divided into tectonic plates riding on top of the slow moving currents of magma in the mantle.

 

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10. Explain that most major geological events (e.g., earthquakes, volcanic eruptions, hot spots and mountain building) result from plate motion.

 

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11. Use models to analyze the size and shape of Earth, its surface and its interior (e.g., globes, topographic maps, satellite images).

 

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12. Explain that some processes involved in the rock cycle are directly related to thermal energy and forces in the mantle that drive plate motions.

 

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13. Describe how landforms are created through a combination of destructive (e.g., weathering and erosion) and constructive processes (e.g., crustal deformation, volcanic eruptions and deposition of sediment).

 

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14. Explain that folding, faulting and uplifting can rearrange the rock layers so the youngest is not always found on top.

Materials

• Box

• Cutting instrument

• Blue paper

• Cardboard strips

• Tape or glue

• Writing material

• Worksheet
  

Procedure

1. The teacher will show a soft boiled egg (cut in half with the shell still on) and make a comparison between the soft boiled egg and the layers of the earth. The yolk, which is a little "runny," is the core of the earth. The white of the egg is like the mantle and the shell represents the crust of the earth.

2. Divide the students into groups of two or three.

3. Given Plate Tectonic worksheet, students will name the layers of the earth.

4. The students will make a box that will be used to replicate the movement of plates on the earth. They will use the box to demonstrate the convergence and divergence of the plates of the earth. To build the box, students will cut a long very thin strip in the top and will cut holes in both of the sides. (See worksheet for illustration.)
   
   
   
   
   
   
   
   Step 1. Take two sheets of blue paper to represent the oceanic plate. On both sheets place a triangular tube to represent the plate with an oceanic and continental crust. (Brown cardboard works well.)
   
   Put the unattached sides of the papers through the slit so that only about half of the paper is showing. When one paper is pulled down, this represents the convergence of the plates. When the paper is pushed up, this represents the divergence of the plates.
   
   Step 2. Move only the sheet with the cardboard attached so that the cardboard comes to the edge of the slit. This represents the ocean plate disappearing beneath the edge of the continent. This is called subduction. This sinking of the oceanic plate into the mantle below the edge of the continental crust results in "plate-pull" and may be one of the major forces driving plate tectonics. Subduction also results in volcanic eruptions and very deep ocean trenches.
   
   Step 3. On the plain sheet of blue paper, attach another triangle so that this also has a continental and an oceanic crust. Now pull both sheets of blue paper from the bottom. If you do this carefully, one of the triangles will go on top of the other showing the development of mountains when convergence occurs.
   
   Step 4. If the layers are moved toward the sides of the box, the students can see the action of fault lines moving in an earthquake. This is called a transform fault.

5. Have the students go to http://www.ucmp.berkeley.edu/geology/tectonics.html to see an animation of plate tectonics.
   

6. Have the students write a paragraph to explain what they have just done. They need to include a diagram showing at least one of the four steps above.

Vocabulary

Continental crust — The land crust of the earth.

Core of the earth — There are really two cores, an inner core which is solid and is about 4300° C, and a core which is liquid around the inner core. They are composed of mostly iron with about 10% sulfur. (There is some “new” information that uranium may be in the core in quantity and may be responsible for much of the earth’s inner heat.)

Convergence — The act of moving toward each other and colliding.

Crust — The crust is much thinner. It is rocky and brittle, so it can fracture during plate movements, resulting in earthquakes.

Divergence — The act of moving away from each other. Where plates diverge, hot molten rock rises and cools, adding new material to the edges of the mid-oceanic plates. This process is known as sea-floor spreading.

Mantle — The mantle goes around the core and is solid. It comprises most of the earth's mass. The temperature is about 1000° C.

Oceanic crust — The crust underlying the ocean basin. This layer is much thinner than the earth’s continental crust and is young.

Plates — The earth’s surface is broken into seven large and many small moving plates, each about 50 miles thick. They move relative to one another an average of a few inches a year or about as fast as fingernails grow.

Plate Tectonics — This is a geological theory which says that the surface of Earth is broken into large plates. The size and position of the plates change over time. It was developed by Alfred Wegener. Unfortunately, he died before his theory was accepted as a major paradigm in modern geomorphology.

Transform fault — Plates moving horizontally against each other.

Assessment

Enrichment

Lightweight tissue paper could be attached to the triangular tube and laid over the blue “ocean” paper. If the blue paper is then pulled, the tissue paper will wrinkle and ball up at the subduction zone becoming a mountain range.