HOW DEEP IS THE OCEAN (AND WHERE)?
Learning the layout of the Earth underneath the deep, blue seas
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Author Contact Information
Katy Myrick, Austin Academy, Garland ISD, Garland, Texas
Steve Stevenoski, Lincoln High School, Wisconsin Rapids, Wisconsin
Rick Ford, Fossil Hill Middle School, Keller ISD, Ft. Worth, Texas
Through the use of mapping skills and Inquiry based problem solving, students will predict and then analyze the layout of the tectonic plates that form the oceans’ floor. Students will also compare the depth of various regions in the ocean with the geologic age to identify relationships between ocean depth and the age of the seafloor in that area.
Middle School Science (grades 6, 7, and 8)
NSES Standard A – Science as inquiry
IDENTIFY QUESTIONS THAT CAN BE ANSWERED THROUGH SCIENTIFIC INVESTIGATIONS. Students should develop the ability to refine and refocus broad and ill-defined questions. An important aspect of this ability consists of students' ability to clarify questions and inquiries and direct them toward objects and phenomena that can be described, explained, or predicted by scientific investigations. Students should develop the ability to identify their questions with scientific ideas, concepts, and quantitative relationships that guide investigation.
USE APPROPRIATE TOOLS AND TECHNIQUES TO GATHER, ANALYZE, AND INTERPRET DATA. The use of tools and techniques, including mathematics, will be guided by the question asked and the investigations students design. The use of computers for the collection, summary, and display of evidence is part of this standard. Students should be able to access, gather, store, retrieve, and organize data, using hardware and software designed for these purposes.
DEVELOP DESCRIPTIONS, EXPLANATIONS, PREDICTIONS, AND MODELS USING EVIDENCE. Students should base their explanation on what they observed, and as they develop cognitive skills, they should be able to differentiate explanation from description--providing causes for effects and establishing relationships based on evidence and logical argument. This standard requires a subject matter knowledge base so the students can effectively conduct investigations, because developing explanations establishes connections between the content of science and the contexts within which students develop new knowledge.
There are some key ideas in this lesson that differ from the traditional method of presenting plate tectonic theory. The emphasis of this activity is to look at the places of active spreading on the ocean floor, rather than to look at the continental landmasses and their relationship to the super continent Pangea.
Familiarize yourself with the location of mid ocean ridges and trenches (back arc regions) in the Earth’s oceans.
Poster size world map (1 per classroom)
Student Maps – 1 per group of 2 (master available as GIF image that can be downloaded here.)
Hint: If possible, print geologic atlas on transparency for students to lay over paper bathymetry map.
Color markers – 3 colors per group
Rulers – 1 per group
This activity can be conducted in 1 to 2 50-minute class periods.
Engagement and Exploration (Student Inquiry Activity)
1. Introduction – Discussion - Ask the students to determine where they think the deepest part of the Ocean is. Have each student write why they think that their location is correct on a post it note or note card. Have the students attach the post it or note card on the map at the location they think will be the deepest. Read each of the student explanations to the class and have the students organize the responses into categories based upon the reasoning behind their chosen location. Keep this tally as a reference for the future.
2. Review measurement and scaling with the students, emphasizing that in this activity they are collecting data and drawing conclusions and that their answers may differ.
3. Familiarize the students with the maps for the activity and work toward student mastery of the legend and map information prior to starting the activity.
Students should have some preconceived notions of what the seafloor is like. Some of these ideas should have arisen during the group discussions and the first inquiry about the deepest ocean. This is an ideal time to talk about how different scientists may interpret data differently. Try to make it clear that in this activity the students are to form their own best answers. There will be time for peer review and discussion, but students should follow what they think is the best scientific method.
Elaboration (Polar Applications)
Tectonic plates are an integral part of the Polar Regions. Both the Arctic and Antarctic are converging points for a number of tectonic plates. The Arctic and the Antarctic are active volcanic areas due to subduction and spreading centers in these areas. Despite the extreme temperatures of these areas, volcanic and tectonic systems are not affected by the cold.
Exchange (Students Draw Conclusions)
Evaluation (Assessing Student Performance)
At the conclusion of this activity, students should have a map as a finished product for assessment. This map, coupled with the discussion questions, should provide teachers with adequate assessment of students’ understanding.
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