Plate Tectonics

Phyllis J. Robinson Mount Vernon Elementary School
10540 South Morgan
Chicago IL 60643
(312) 535 2825

Objectives: After this experience the students should 1. be able to identify the three main parts of the earth 2. be aware that the earth's crust is made up of pieces called plates 3. be able to state the theory of Plate Tectonics 4. be aware that convection currents could cause the earth's crustal plates to move 5. be able to identify plate divergence as a possible explanation of Continental Drift, seafloor spreading, and volcanic activity near the Mid Atlantic Ridge 6. be able to identify plate convergence as a possible explanation of earthquakes, volcanoes, mountain building, subduction and the rock cycle. Materials needed: 1. One chart showing the three main parts of the earth 2. A boiled egg and a plastic knife for each group of five students 3. A puzzle showing the large plates of the earth (one per student) 4. A hot plate, aluminum cake pan, water,and balsa wood pieces. (one set) 5. A 750 ml beaker, a pill bottle, two-hole rubber stopper to fit the pill bottle, glass rods, hot water, cold water, two pennies, and food color (one set per group of five students) 6. A sheet of butcher paper 2 m long, 2 demonstration tables, a silhouette of Africa and South America, a marking pen (one set up per class) 7. 2 damp wash cloths per group, 4 popsicle sticks per student, a lump of clay for each student 8. A shoe box, small garbage bag, scissors, newspaper, two boards (30cm X 30cm X 5cm), five pounds of sand, water to dampen the sand Strategy: Activity I Show students the core, mantle, and crust of the earth using a chart. Pass a boiled egg and a plastic knife to each group of two. Have one of the students cut the egg in half. Each person gets half of the egg and will use it as a model to discover the three main parts of the earth. Tell the students that the cracked shells represent the part of the crust called plates. Activity II Pass a jigsaw puzzle to each student and instruct them to put it together. Students should discover that the puzzle represents the earth's crustal plates. They should identify the continents and oceans. They should observe that some plates are composed of all continent, all ocean, and a combination of both. Introduce terms by having students move two adjacent plates apart (Divergence); move two plates together (Convergence); and move two plates so that one moves up and the other down with the pieces rubbing past each other (Transformation). Activity III Tell the students the theory of Plate Tectonics. The earth's crust is composed of seven or eight major plates and several smaller ones. These plates move. Activity IV Let students relate science equipment to the earth's model. Hot plate - core, water (in an aluminum pan) - mantle, balsa wood chips - crustal plates. Heat the water to boiling. Put chips in the center of the pan. Students should identify the boiling water as a convection current that causes the balsa wood chips (crustal plates) to move. Activity V Each group of four students will get a 750 ml beaker filled with cold water. They will fill a pill bottle with hot water, 3 drops of food color and two pennies to keep it from floating. They will cut 2 pieces of glass tubing 8 cm long (straws can be substituted for the glass tubing). Insert a tube into each hole of a two hole rubber stopper and position the tubes so that one sticks out of the stopper more than the other. Insert the rubber stopper into the pill bottle. Wipe any colored water off of the bottle. Hold it by the rim and lower the pill bottle into the center of the beaker of cold water until it sits on the bottom of the beaker. Keep the pill bottle upright. Students should discover that this is a convection current and the colored water looks like lava coming from a volcano. Activity VI Students will observe a model of diverging plates. The teacher will push two display tables together leaving a small space between them. She will tell the students that the tables represent two Atlantic Ocean plates and the opening represents the Mid-Atlantic Ridge. The teacher will cut off butcher paper two meters long and slide it through the opening (Mid-Atlantic Ridge) so that 5cm of paper is showing on the surface of each table on each side of the ridge. Have two students each label their paper lava/new crust and mark it with a ruler and pen. Have the student helpers pull out 5cm more of butcher paper and mark it lava/new crust. Have them also tape a silhouette of South America on the left crust and Africa on the right crust. Have helpers pull out 5cm more of butcher paper and mark it as before. Continue the previous steps until the students are able to discover that the seafloor is spreading because new crust is being added. The Atlantic Ocean is getting larger. The continents are moving apart. Volcanoes are forming volcanic mountains and islands along the Mid-Atlantic Ridge. The Atlantic crustal plates are moving apart. (Divergence) Activity VII Students should discover that while the Atlantic plates are diverging, the Pacific plates are converging. Ten students will be Pacific crust. They will hold hands to form a circle to define the size of the earth. Drop hands. Ten more students will represent the new Atlantic crust. They will join the earth's circle two at a time at the same place. They will diverge and push the Pacific plates closer together (converge). As more and more new Atlantic crust join the line, some of the Pacific plates will move in front of the other Pacific crustal plates to make room. (This represents subduction). Students should discover that as the new Atlantic crust diverged the Pacific crust converged. They should discover that the Pacific crust made room for the new crust by moving out of the way through subduction. Activity VIII Teacher will explain terms subduction, Asthenosphere, and rock cycle. Activity IX Students should be told that continental crust does not subduct into the Asthenosphere. Students will use two damp wash cloths to represent continental crust. They will diverge them and discover that volcanoes could develop between the plates. They will converge (push together) the continental crust. They should discover that the rolls and the folds look like mountains. Use popsicle sticks to form anticlines and synclines. Students should discover that pressure which forms mountains and valleys also causes breaks called faults and sudden movements called earthquakes. Use clay to form various mountain forms. Activity X Use a Fault Box to observe a model of an earthquake. Cut the bottom of a shoe box with scissors. Cut a small garbage bag so that it will hang down through the bottom of the shoe box by about l0 cm. Attach the bag to the side of the shoe box. Cover the area with newspaper. Place two boards (30cm X 30cm X 5cm) on the newspaper side by side. Place the shoe box on the crack between the board so that half of the box is on each side. Pull up the garbage bag so that it forms the bottom of the shoe box. Fill the box with wet sand. Pack it down and smooth it out. Have a helper hold the box steady. Have students come up in groups of four or five. Let them observe what happens when one of the boards slides out from under the fault box. Return the board and smooth the sand. Slide both boards apart until they are separated 15cm. Do not pull boards all the way out. Return the boards and smooth the sand. Slide both boards apart and push back together. Return the boards and smooth the sand. Slide both boards alternately up and down, back and forth so that the sides rub against each other. Observe results after each trial. Bibliography: Fariel, Robert, Earth Science (teacher's edition) Menlo Park, California, Addison
Wesley Publishing Co. l984 p 502 (Simulating seafloor spreading)

Tillery, Bill W. Earth Science Teacher's Resource Binder Lexington, Mass. D.C.
Heath and Co. l987 (Convection currents-Chapter l5 Lab A p. 56) (Fault box Chap.
l6 Lab. B p.62)

Wynn, Douglas E. Focus on Earth Science Teacher Resource Book, Columbus, Ohio,
Charles E. Merrill Publishing, l988 (Crustal Plates - Teaching Master l6-l)
(Types of Plate boundaries - Teaching Master l6-2)

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