TIS THE SEASON FOR SCIENCE

Transcription

1 School District of Palm Beach County Secondary Education TIS THE SEASON FOR SCIENCE Winter Enrichment Activities for Science Plate Tectonics 8th grade

2 Teacher Introduction The usage and implementation of the activities contained in the winter packets are optional and voluntary. The activities were selected based on traditionally difficult areas of student mastery while at the same time providing highly engaging and fun discovery. Suggested ways to implement the winter packet: Extra Credit Team Projects Mini Science Project Suggested alternative to winter break activities: Suggestions for checking for comprehension: Review assessment questions that are embedded within the activities. Discuss student findings after students return to school. Provide students an extension to the activities (Research paper, project, etc )

3 Introduction Who would have ever guessed that science could be so much fun! Hands-on experiments, discovery of cause and effect relationships, and engaging activities have captured students interests in classrooms for years. However, classrooms and laboratories aren t the only places to experience the joys of science. This winter packet has been provided with just that in mind. Students, you have the opportunity to share the fun of scientific experiments and discoveries at home with family and friends! What is Science? The study of science is designed to help discover information about the natural world in which we live. Although it is a means of collecting facts (data) through an organized and reproducible manner, science includes observations, predictions, questions, trials and errors. In other words, it is a method for providing understanding to an ever changing world. Science does not provide all the answers. However, answers gathered through inquiry using the scientific method explain daily events. Therefore, the great thing about science is that anyone who studies it is exposed to new discoveries all the time. Purpose of the Winter Activities The winter activities were selected to allow students to experience science fun over the winter break while simultaneously supporting the traditionally difficult areas of student mastery. This method of home-school academic connection is a great means to maintaining acquired skills while students are enjoying their winter break. Activities are identified by Next Generation Sunshine State Standards specifically targeted to rigorous expectations for the students. Each activity has been selected due to its high level of engagement and interest. Background information is included for each activity in order to provide students with a supportive platform to complete the contents within.

4 8 th Grade Science Winter Activities Name: Section Actions at Plate Boundaries - Plate Tectonics SC.7.E.6.5 AA Explore the scientific theory of plate tectonics by describing how the movement of Earth's crustal plates causes both slow and rapid changes in Earth's surface, including volcanic eruptions, earthquakes, and mountain building. Purpose: To introduce the concept of plate tectonics and to explain the existence of various geologic features located near plate boundaries such as volcanoes, mountains, trenches, rift valleys, mid-ocean ridges, island arcs, and earthquakes. Materials: One canister of play-doh (larger size), plate tectonics map (included) notebook paper, plastic knife Background Info: Scientists now have a fairly good understanding of how the plates move and how such movements relate to earthquake activity. Most movement occurs along narrow zones between plates where the results of plate-tectonic forces are most evident. There are four types of plate boundaries: Divergent boundaries -- where new crust is generated as the plates pull away from each other. Convergent boundaries -- where crust is destroyed as one plate dives under another. Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other. Plate boundary zones -- broad belts in which boundaries are not well defined and the effects of plate interaction are unclear. Divergent boundaries Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle. You can picture two giant conveyor belts, facing each other but slowly moving in opposite directions as they transport newly formed oceanic crust away from the ridge crest. Perhaps the best known of the divergent boundaries is the Mid-Atlantic Ridge. This submerged mountain range, which extends from the Arctic Ocean to beyond the southern tip of Africa, is but one segment of the global mid-ocean ridge system that encircles the Earth. The rate of spreading along the Mid-Atlantic Ridge averages about 2.5 centimeters per year (cm/yr), or 25 km in a million years. The volcanic country of Iceland, which straddles the Mid-Atlantic Ridge, offers scientists a natural laboratory for studying on land, the similar processes also occurring along the submerged parts of a spreading ridge. Iceland is splitting along the spreading center between the North American and Eurasian Plates, as North America moves westward relative to Eurasia.

5 In East Africa, spreading processes have already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. East Africa may be the site of the Earth's next major ocean. Plate interactions in the region provide scientists an opportunity to study firsthand how the Atlantic may have begun to form about 200 million years ago. Geologists believe that, if spreading continues, the three plates that meet at the edge of the present-day African continent will separate completely; allowing the Indian Ocean to flood the area and making the easternmost corner of Africa (the Horn of Africa) a large island. Procedure: Divergent Boundary: You are going to simulate a divergent boundary. Take your Play-Doh out and make one large pancake. (Approximately 10 cm in diameter) The pancake represents the Earth s lithosphere; Your desk/table will simulate the asthenosphere. 1. How do the plates move at a divergent boundary? _ Simulate this motion on your pancake ; Hold your pancake in your hands, thumbs on top and fingers on the bottom approximately 2 cm apart. GENTLY, push up with your fingers as you pull apart with your thumbs. Pull until a fissure (gap) appears, STOP and place your Play-Doh on the table/desk. 2. What happened to your pancake? 3. What features formed near the center of the pancake? What formed where your fingers pushed up? 4. What will fill in the void left in the middle of your pancake or plates? 5. What feature listed above would be an example of this? 6. On a separate sheet draw a cross-sectional view of your Play-Doh plates.

6 Convergent Boundaries Oceanic Continental If by magic we could pull a plug and drain the Pacific Ocean, we would see a most amazing sight -- a number of long narrow, curving trenches thousands of kilometers long and 8 to 10 km deep cutting into the ocean floor. Trenches are the deepest parts of the ocean floor and are created by subduction. Off the coast of South America along the Peru-Chile trench, the oceanic Nazca Plate is pushing into and being subducted under the continental part of the South American Plate. In turn, the overriding South American Plate is being lifted up, creating the towering Andes Mountains, the backbone of the continent. Strong, destructive earthquakes and the rapid uplift of mountain ranges are common in this region. Oceanic-continental convergence also sustains many of the Earth's active volcanoes, such as those in the Andes and the Cascade Range in the Pacific Northwest. The eruptive activity is clearly associated with subduction, but scientists vigorously debate the possible sources of magma: Is magma generated by the partial melting of the subducted oceanic slab, or the overlying continental lithosphere, or both? Procedure: Convergent Boundary: Oceanic Continental Make one egg with your Play-Doh (which represents the continental crust of the Earth s lithosphere) and one pancake (which will represent oceanic crust). Use half of your Play-Doh for each. 1. What types of forces are present at a convergent boundary? Simulate these forces on your continental and oceanic crust (make sure the ocean crust sinks since it is composed of denser material). 2. What happens at the boundary? Did they slide past easily? What force would be generated by two plate size masses moving past one another? 3. Pinch on top of the continental egg. What features will these represent, where the two plates meet? Refer to diagram above.

7 4. What are real examples of these features? 5. What feature would have formed on the oceanic plate at the junction of the two plates? What process produced this? 6. On a separate sheet draw a cross-sectional view of your Play-Doh plates. Convergent Boundaries (continued) Oceanic Oceanic As with oceanic-continental convergence, when two oceanic plates converge, one is usually subducted under the other, and in the process a trench is formed. The Marianas Trench (paralleling the Mariana Islands), for example, marks where the fast-moving Pacific Plate converges against the slower moving Philippine Plate. The Challenger Deep, at the southern end of the Marianas Trench, plunges deeper into the Earth's interior (nearly m) than Mount Everest, the world's tallest mountain, rises above sea level (about 8854 m). Subduction processes in oceanic-oceanic plate convergence also result in the formation of volcanoes. Over millions of years, the erupted lava and volcanic debris pile up on the ocean floor until a submarine volcano rises above sea level to form an island volcano. Such volcanoes are typically strung out in chains called island arcs. As the name implies, volcanic island arcs, which closely parallel the trenches, are generally curved. Magmas that form island arcs are produced by the partial melting of the descending plate and/or the overlying oceanic lithosphere. The descending plate also provides a source of stress as the two plates interact, leading to frequent moderate to strong earthquakes. Procedure: Convergent Boundary Oceanic Oceanic Make two equal sixed pancakes with your Play-Doh which represent plates of oceanic crust in the Earth s lithosphere. 1. What forces are present at a convergent boundary?

8 Simulate these forces on your oceanic crust (make sure one sinks beneath the other ocean crust sinks since usually one plate is more dense than the other). 2. What happens at the boundary? 3. What two features will form near the center where the two plates meet? One forms on the top plate, the other forms on the bottom plate. 4. On a separate sheet draw a cross-sectional view of your Play-Doh plates. Convergent Boundaries (continued) Continental - Continental The Himalayan mountain range dramatically demonstrates one of the most visible and spectacular consequences of plate tectonics. When two continents meet head-on, neither is subducted because the continental rocks are relatively light and, like two colliding icebergs, resist downward motion. Instead, the crust tends to buckle and be pushed upward or sideways. This process is continuing today and exceeds the rate of erosion. The Himalayas are actually increasing in elevation.

9 Procedure: Convergent Boundary Continental Continental Make two eggs with your Play-Doh which represent the continental crust of the Earth s lithosphere. 1. Describe the plate motion at a convergent boundary. Simulate this motion on your continental continental boundary and push the two continent eggs together. 2. What happens at the boundary? Does all the material go up, or does some of it go down? 3. What features will form near the center where the two plates meet? 4. On a separate sheet draw a cross-sectional view of your Play-Doh plates. Transform Fault Boundary The zone between two plates sliding horizontally past one another is called a transform-fault boundary, or simply a transform boundary. Most transform faults are found on the ocean floor. They commonly offset the active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes. However, a few occur on land, for example the San Andreas Fault zone in California. (Aerial view of San Andreas Fault) The San Andreas Fault zone, which is about 1300 km long and in places tens of kilometers wide, slices through 2/3 of the length of California. Along it, the Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of about 5 cm/yr. Land on the west side of

10 the fault zone (on the Pacific Plate) is moving in a northwesterly direction relative to the land on the east side of the fault zone (on the North American Plate). Procedure: Transform Fault Boundary Make one pancake with your Play-Doh. 1. What forces are present at a transform boundary? Use a plastic knife to fault (cut the pancake in half as smoothly as possible) your boundary, and then draw a line across the fault line to represent a stream. Now apply forces to the lithosphere by sliding them past one another. 2. What happens to the plates? Do they slide easily? Do they stick together? 3. What features or phenomena will occur near the plate boundary you have created? 4. On a separate sheet draw a cross-sectional view of your play-doh plates. Summary: Create a concept map or write a summary paragraph to help demonstrate what you learned. Additional PowerPoint reference can be found at

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12 Informational text and pictures were taken from the USGS: Understanding Plate Motions at Play-Doh activity and questions were adapted from a lesson developed by Ray Crowell at Boca Raton High School, Boca Raton, Florida. MISSION STATEMENT The School District of Palm Beach County is committed to providing a world-class education with excellence and equity to empower each student to reach his or her highest potential with the effective staff to foster the knowledge, skills, and ethics required for responsible citizenship and productive careers.