Title: The Ocean Floor: How Puzzling Can It Be?

Transcription

1 Title: The Ocean Floor: How Puzzling Can It Be? (Ocean Floor Mapping) Grade Level(s): 6-8 Introduction: In 1804, an expedition led by Meriwether Lewis and William Clark, had one main purpose. It was to map America s interior and to discover its resources. The two-year journey took them across western North America. Along the way, they observed the land, water, air, and living things. Together, these four things make up everything that is on and around planet Earth. Scientists divide Earth into four spheres: the lithosphere, hydrosphere, atmosphere, and biosphere. Earth s oceans, lakes, rivers, and ice form the hydrosphere. Most of the hydrosphere consists of the salt water in the oceans, but fresh water is also part of the hydrosphere. Oceans cover more than two thirds of Earth. Students can make puzzles from world maps, dramatizing how much of the globe is covered by ocean. This is known as geological oceanography. Learner Objectives: The student will be able to involve integration of information and to use several methods of problem-solving. The student will be able to work with maps, not only for providing content, but for exercising spatial skills. The student will be able to understand the earth s physical geography by using different types of world maps. The student will be able to explain sea floor topography. (Refer to Note at end of lesson plan activity) Florida Sunshine State Standards: Science: SC.D.1.3.5/SC.F.2.3.4; Math: MA.E Competency Based Curriculum: Math: M/J-I-V-1-A/M/J-3-VI-2-A; Science: M/J-3-II-5-B I-A-16

2 Materials: World maps of varying sizes, glued onto poster board Scissors Glue Poster board Envelopes Activity Procedures: 1. Divide students into groups of 2-4 and give each group a world map. 2. Decide on general sizes for puzzle pieces and have at least some groups make pieces the same shape. Allow each group cut its map into puzzle-like pieces. 3. Allow each group to place the pieces into envelopes marked with a letter. 4. Allow groups to exchange envelopes and then reassemble the world. 5. As they assemble the puzzles, allow students to name features on the maps. On the board, make a list of features for all the groups to find specific oceans and seas, the continents, mountain ranges, the equator, prime meridian, the poles, and the Tropics of Capricorn and Cancer. 6. Allow students to create and place in the envelope a list of features specifically found on that map, such as oceanic ridge systems, trenches, islands, and continental shelves for a map showing ocean floor topography. The next group of students must locate these features. 7. Allow the students again to exchange envelopes and to assemble the world, finding the features listed by the previous group. 8. Using a large map at the front of the class, allow each group to come up and locate a feature called out by the teacher. Each group gains points for correct locations. Student Assessment: Allow students to answer critical thinking questions assigned by the teacher. a. Compare the area of the Atlantic Ocean map (water removed) to a wall map of the world and find the labeled continental shelves, abyssal plains, continental slopes, trenches, and ridges. b. How can mapping and photography help determine the formation of the ocean floor? Students will be assessed on their group work reassembling the puzzle, their identification of the required features, and the list of features they compile for other students to find. Activity Extensions: 1. Allow students to find a variety of maps, including weather maps, and any number of specialized maps, such as those showing population or distribution of natural resources and encourage them to convey their knowledge to family members at home. (Social Studies/Science) I-A-17

3 Activity Extensions: (Continued) 2. Provide mathematical problems for students to solve with the scales used by the U.S. Geological Survey (USGS) on topographic maps. The USGS is responsible for making topographic maps and the scale is based on the metric system. (Math) Note: Topographic maps can be obtained at public libraries, the USGS, or from county offices. Home Learning Activity: Challenge students to make a model ocean profile using a small aquarium (pan), sand, and water. They can make their own seawater by dissolving 35 grams of salt for every liter of water. They may bury a metallic object at a specific location and challenge others to find it without disturbing other parts of the ocean floor. Remind students that a profile is a side view of the ocean floor. Vocabulary: hydrosphere, oceanography References/Related Links: Glencoe (2000). Science Voyages. Westerville, OH: Glencoe/McGraw Hill. I-A-18

4 The Ocean: How Puzzling Can It Be? Reading Passage For centuries, people have been challenged by the mysteries that lie beneath the blue depths of our ocean planet. Very little was known about the ocean until late in the nineteenth century, although nearly three-quarters of the planet is covered by ocean or seawater. Myths and misconceptions abounded. We used to think that the ocean depths were devoid of life. We thought that the sea floor was flat and that it was the same age as the continents. How different a picture we now have of the ocean as the sea has begun to yield its secrets. In the 1870s, the HMS Challenger left England and sailed the world s oceans, throwing out weighted lines and taking soundings to measure the depths of the Atlantic, Pacific, Indian, and Arctic Oceans. For the first time, scientists had an inkling of the contours of the ocean floor, took samples of the plants and animals, and measured differences in water temperature and salinity. But the cold, dark water and extreme pressure of the depths kept scientists from knowing the secrets of the deep abyss. Today s scientists have overcome many of the challenges of the deep by using more sophisticated tools. They can send manned submersibles and sampling devices to plumb the ocean depths., taking photographs and samples of animal life and sediment to bring back to the surface for further study. Even space technology enters the picture. satellite photos taken of the ocean provide a wide range of information, including water temperature and depth, seafloor topography, and the plankton populations. Using sonar and satellite data, scientists have been able to generate a new map of the ocean floor, thirty times more accurate than the best previous map. For scientists, there is a broader understanding of how the ocean basin formed and continues to evolve. Molten Magma from earth s interior spews out at the mid-ocean ridges, spilling over to either side and hardening to rocky basalt. As the crust pushes away from the ridges, it cools and thins, forming new seafloor and thus widening the ocean here. As this portion of the ocean floor widens, a section of the seafloor elsewhere is slowly sliding beneath the crust, becoming part of earth s magma once again. Plate tectonics, the theory of earth s crustal plates, thus helps explain ocean formation. New observations also give scientists a greater understanding of the dynamic nature of Earth s water and oxygen cycles and how planetary winds affect ocean currents. Data allow scientists to hypothesize about global weather systems, earthquake and volcanic activity, and climatic trends of global consequence. I-A-19

5 The Ocean Floor: How Puzzling Can It Be? FCAT Questions Directions: Read the passage, then answer all the questions below. Answer multiple-choice questions by circling the letter of the answer that you select. Write your answer to the Read, Think, and Explain question on the lines provided. 1. A new map of the ocean floor has been generated by which technique(s)? A. Space technology B. Sonar and satellite data C. Manned submersibles D. Oceanic photography Answer: B 2. The new ocean floor map shows which of the following features? A. Mid-Ocean Ridge bisecting the Atlantic Ocean B. Flat Pacific Ocean floor C. Generalized underwater volcanoes D. Molten magma Answer: A 3. Ocean formation is best explained by which of the following theories? A. Global warming B. Geological oceanography C. Oceanic topography D. Plate tectonics Answer: D 4. Why was it important for the author to determine longitude? I-A-20