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The Face of Change Modified from Earthquakes and Plates Tectonics (http://visearth.ucsd.edu/VisE_teach/lessons/EQ+PT_LP.html) and A Model of Sea Floor Spreading (http://www.ucmp.berkeley.edu/fosrec/Metzger3.html) Modified by: Kirstin Bittel Time: 3-5 Periods Preparation Time: 10-15 minutes Materials: Boxes of varying sizes Long strips of paper taped together Copies of plate boundary maps (1 per student) Plate boundary overhead (Available online from http://www.geophysics.rice.edu/plateboundary/plate.8.11.pdf) Abstract Students will spend several days building models of the plate boundaries to “see” what happens at each border. Students will then identify different boundary types on a world map based upon the geologic events that occur at those boundaries. Purpose – Students will explain the connection between geologic events and plate motion. Objectives Students will be able to: 1. Create a model that demonstrates what occurs at crustal boundaries. 2. Identify and label different boundary types on a world map. National Science Education Standard: CONTENT STANDARD D – Earth and Space Science Energy In The Earth System The outward transfer of earth's internal heat drives convection circulation in the mantle that propels the plates comprising earth's surface across the face of the globe. Geochemical Cycles The earth is a system containing essentially a fixed amount of each stable chemical atom or element. Each element can exist in several different chemical reservoirs. Each element on earth moves among reservoirs in the solid earth, oceans, atmosphere, and organisms as part of geochemical cycles. Movement of matter between reservoirs is driven by the earth's internal and external sources of energy. These movements are often accompanied by a change in the physical and chemical properties of the matter. Carbon, for example, occurs in carbonate rocks such as limestone, in the atmosphere as carbon dioxide gas, in water as dissolved carbon dioxide, and in all organisms as complex molecules that control the chemistry of life. The Origin And Evolution Of The Earth System Interactions among the solid earth, the oceans, the atmosphere, and organisms have resulted in the ongoing evolution of the earth system. We can observe some changes such as earthquakes and volcanic eruptions on a human time scale, but many processes such as mountain building and plate movements take place over hundreds of millions of years. Teacher Background Convergent boundaries occur where plates push together, causing subduction and collision. As a result, faults form. The faults that form at a Convergent boundary are called reverse faults, or thrust faults. When an ocean plate is subducted, a strato-volcano mountain range is formed on the overriding plate. When two continental plates collide, a collision zone develops and the plates are thrust upward, forming large mountain belts, like the Himalayas. Divergent boundaries occur when two plates move apart and new crust is created. At divergent margins, plates move apart and new crust is formed. This usually occurs at a Mid-Ocean Ridge, like the Atlantic Ocean, but divergent margins can also occur on land. An example of a land divergent boundary is the Great Rift Valley in Africa. Divergent boundaries that occur under continental crust pull pieces apart to form parallel basins and ranges. Divergent boundaries that occur under the ocean cause spreading across mid-ocean ridges that is symmetrical and normal faulting predominates. Earthquakes are weak but common. Magma cooling at mid-ocean ridges continuously records variations in the polarity of the Earth's magnetic field. Transform boundaries occur when two pieces of crust slide past each other, forming a strike-slip fault. Where tectonic plates slide past each other along a strike-slip fault, many strong, shallow earthquakes occur. Continental transform faults can cause crustal uplift (mountains) and subsidence (basins) due to compression and extension. Related and Resource Websites Mountain Maker, Earth Shaker http://www.pbs.org/wgbh/aso/tryit/tectonics/ Discovering Plate Boundaries http://www.geophysics.rice.edu/plateboundary/downloads.html Activity Prior to the Lesson 1. Have students begin bringing in boxes. Any type of box will work (shoeboxes, packing boxes, etc.). They can visit the local grocery store or the school cafeteria. Ideally you will need 1 –2 boxes per group. Part One (2-3 Days) 1. Briefly review the three boundary types with the class [convergent, divergent, and transform]. 2. Ask students if they know what drives plate tectonics. Ask if they know what a convection cell is (If not demonstrate). Knowing what they do about the earth’s structure how do they think convection cells could drive plate tectonics? (This cycling of the mantle pushes the plates above the mantle much like a conveyor belt pushes groceries. The mantle is extremely hot, and anything that is subducted melts and becomes magma.) 3. Tell students that over the next few days they will be conducting simulations to see what happens at plate boundaries. They will be using models to help them since we cannot directly observe the Earth’s layers or plate motion. Around the room are the boxes the students brought in. Each group needs to get one box to represent the Earth and several lengths of paper. Use those papers to represent crustal or mantle material. Their task is to use those materials to make a model that will demonstrate what happens at each type of boundary. (If the students get stuck creating a model, a good example is available at http://www.ucmp.berkeley.edu/fosrec/Metzger3.html). 4. After students have investigated all boundary types (divergent, transform, and convergent: ocean vs. ocean, ocean vs. continent, and continent vs. continent) ask the students the following questions: What do you think happens at a divergent boundary? What geologic event do you think happens there? [Spreads apart-Volcanoes and Earthquakes] What do you think happens at a transform boundary? What geologic event do you think happens there? [Sliding-Earthquakes] What do you think happens at a collision boundary? [Crashing] What happens when an ocean plate collides with a continental plate? What geologic event do you think happens there? [The ocean plate subducts-Volcanoes on land or Volcanic Mountains] What happens when a continental plate collides with a continental plate? What geologic event do you think happens there? [They crash and form Mountains] What happens when an ocean plate collides with another ocean plate? What geologic event do you think happens there? [The older/denser plate subducts-Volcanoes] *NOTE TO TEACHER: If time becomes an issue, you might wish to assign student-specific boundaries to research so that not all students are responsible for all boundaries. Part Two (1-2 Days) 1. Review content from previous days. What questions do students have? What do they need clarified? 2. Distribute the maps of plate boundaries. Have students discuss the way they believe each plate is moving prior to the next phase. If they cannot determine the direction of motion based upon the geologic features then assist them. A nice color map for teachers is available at http://volcano.und.nodak.edu/vwdocs/Submarine/plates/ or at http://media.maps101.com/SUB/WORLD_THEMATIC/tectonic.gif 3. Tell the groups to use the information they have just shared with each other to label the plate boundaries according to the type of the boundary they are. Have students select their own colors, but they MUST make a key. 4. Once groups have colored their maps, have a few students share their group’s findings. Discuss similarities and differences. Take this opportunity to correct any misconceptions. Closure Discuss this website with students to close the lesson and sum up the students’ findings. As you show each type of boundary, discuss the land formations and locations where these events occur in the world. If you have access to a computer show the following site to show your students; it might be helpful. It shows a computer model of plate interactions and can help solidify the students’ beliefs and clarify any misconceptions. (http://www.pbs.org/wgbh/aso/tryit/tectonics/shockwave.html) If you do not have computer, use overhead transparencies and pictures of boundary types. Wonderful images are available from www.google.images.com. Embedded Assessment Are students working together to create a working model? Does the model explain what happens at the boundaries? Can the students correctly identify boundary types? Homework Write a 2-3 sentence conclusion in your science notebook. Conclusions should tell what you learned and be thought provoking. What do they think the earthquake locations might tell us?