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Earth seafloor crust

Earth seafloor crust (NOAA, Wikimedia Commons)

STEM in Context

Plate Tectonics

Digital Programs Team

Summary

The surface of the Earth is constantly moving, and earthquakes and volcanoes occur, because of plate tectonics.
The theory of plate tectonics explained (2015) by Minute Earth (2:36 min.).

The Earth is made up of several layers. The topmost layers are made up of the crust and the mantle. These layers are broken up into large interconnected plates. These plates are in constant motion. They float  on a layer of molten rock within the Earth’s mantle. This movement is called plate tectonics

Today, there are seven continents on Earth. But over 250 million years ago, all seven of those continents were one large landmass. That landmass was a supercontinent called Pangea

Scientists believe that after another hundred million years, the continents may drift back together again! Earth’s tectonic plates shift about 2.5 centimetres per year. That may not seem like a lot. But after millions of years, that can add up to many kilometres! 

Movement of tectonic plates
Movement of tectonic plates (Source: U.S. Geological Survey).

The Pacific Plate and the North American Plate are two of the world’s largest tectonic plates. These plates are constantly grinding together or shifting past each other. This happens around places like California. That’s why we see volcanoes and earthquakes in that region.

Starting Points

Connecting and Relating
  • If you had an opportunity to take a vacation in an area known for active plate tectonics processes, would you want to go? Why/why not?
  • Have you ever experienced a plate tectonic event such as an earthquake? If so, describe the sensation you felt.
Relating Science and Technology to Society and the Environment
  • Adventure seekers often choose to climb mildly active volcanic mountains as a challenge. Should they expect rescue workers to assist them if their lives become endangered? Why/why not?
  • Plate movements result in both seismic and volcanic activity that can threaten human safety. Is realistic for people who live in these danger zones to rely on scientists for warnings related to increased geologic activity? Why/why not?
Exploring Concepts
  • What is meant by the term “seafloor spreading”? Who was the first to describe this concept?
  • How can earthquake patterns be explained using the science of plate tectonics?
  • Describe three types of boundaries that exist within Earth’s crust. How do they help support crustal movement?
  • If you live to 80 years old, how far will North America have moved from Europe if the yearly spreading rate is 2.5 cm/year? Is that distance greater than or less than your height? Do you think this represents a significant distance? Why/why not?
Nature of Science/Nature of Technology
  • Global positioning satellites (GPS) orbit Earth and provide valuable data for Earth scientists regarding plate movement. Do you think utilizing GPS for scientific studies around the world has been a good use of this technology? Why or why not?
  • How is the Theory of Plate Tectonics a good example of how science progresses?
  • Should scientists change the name from “Theory of Plate Tectonics” to just “Plate Tectonics”? Why/why not?
Media Literacy
  • The earthquake destruction movie, SAN ANDREAS, was criticized for having many scientific inaccuracies. For example, the destruction was exaggerated and the depiction of the scientific processes involved in plate tectonics were inaccurate. Do you think Hollywood should be more accurate with their depictions of natural processes to educate their audiences while entertaining? Why/why not?
Teaching Suggestions
  • This video can be used to support teaching and learning in Earth Sciences related to tectonics, Earth’s Interior and Earthquakes & Volcanoes. Concepts introduced include Pangea, Continental Drift, plate tectonics, crust, plates, mantle, geological time scales, subduction, theory, volcanoes, mid-ocean ridges, strike slip faults, earthquakes, seismic activity and sediments.  
  • Prior to beginning a discussion on Plate Tectonics, ask students what they know about Continental Drift, who had proposed it, and what difficulties early scientists had getting others to believe them. Then, have the students complete a Vocabulary Preview to cover any new terms they may encounter. Download ready-to-use reproducibles using the Vocabulary Preview learning strategy for this article in [Google doc] and [.pdf] formats.
  • Once the vocabulary preview is complete, show the video above and have the students complete a Video Review learning strategy to reflect on the information presented in the video. Download ready-to-use reproducibles using the Video Review learning strategy for this article in [Google doc] and [.pdf] formats.
  • To complete the lesson, arrange students in small groups and have them take part in a Write-Around Discussion learning strategy to share their understanding of plate tectonics and the processes associated with it. Download ready-to-use reproducibles using the Write-Around Discussion learning strategy for this article in [Google doc] and [.pdf] formats.

Learn more

Plate Tectonics Theory Lesson (Video, 8:50 min - 2016) -- middle school lesson on plate tectonics theory for grades 6-8.

References

Murphy, Brendan J. & Tjeerd H. van Andel. (2019). Plate Tectonics. Retrieved from https://www.britannica.com/science/plate-tectonics

Oskin, Becky. (2017). What is Plate Tectonics? Retrieved from https://www.livescience.com/37706-what-is-plate-tectonics.html