- Earth’s tectonic plates
- How tectonic plates move
- Divergent, convergent, and transform plate boundaries
- Earth’s changing surface and the supercontinent cycle
- Intraplate activity and hotspots
- Describe what a plate is and how scientists can recognize its edges.
- Explain how the plates move by convection in the mantle.
- Describe the three types of plate boundaries and the features of each type of boundary.
- Describe how plate tectonics processes lead to changes in Earth’s surface features.
continental rifting: splitting of a continent at a divergent plate boundary
convergent plate boundary: location where two lithospheric plates come together
divergent plate boundary: location where two lithospheric plates move apart
intraplate activity: geologic activity that takes plates within a plate away from plate boundaries
island arc: line of island volcanoes resulting from subduction of one oceanic plate beneath another oceanic plate
plate: slab of lithosphere that can move over Earth’s surface
plate boundary: location where two lithospheric plates meet
plate tectonics: theory that Earth’s surface is divided into lithospheric plates that move over the planet’s surface
subduction: sinking of one lithospheric plate beneath another
subduction zone: area where two lithospheric plates come together and one sinks beneath the other
transform fault: fracture in rock where one plate slides past another
transform plate boundary: location where two lithospheric plates slide past one another in opposite directions
Introducing the Lesson
Ask students to recall what they know about the lithosphere from previous lessons. (The lithosphere is the brittle outer layer of Earth that includes the crust and part of the mantle.) Tell them that the lithosphere is broken into pieces that can move around on Earth’s surface. Ask students to think about what might happen if the pieces collided or scraped against each other as they moved. Tell them they will find out when they read this lesson.
You can show students animations of the three types of plate boundaries at the first URL below. You can show them a video lecture on types of plate boundaries at the second URL.
http://www.iris.edu/hq/programs/education_and_outreach/animations/11 (video lecture)
The interactive activity “Mountain Maker, Earth Shaker” (see URL below) allows students to build mountains, trigger volcanoes, and create new seafloor with the click of a mouse. Four types of plate tectonic interactions are demonstrated in the activity. A map shows where in the world each type of plate interaction takes place.
If you have students who are visual or kinesthetic learners or have limited English proficiency, teach them about plate tectonics with the drawing exercise outlined at the following URL. The draw-with-me presentation will engage students and help them understand the spatial and movement aspects of plate boundary interactions. Drawing enhances their learning, understanding, and retention; and at the end of the exercise, they will have a set of illustrations for their science notebook that can be used for study and reference.
Have one or more students create a crossword or other word puzzle for at least ten of the lesson vocabulary terms. They can create their puzzle by hand or use a free online puzzle maker (see URL below). Make copies of their puzzle and distribute them to other students to solve as a review of lesson vocabulary.
The inquiry activity at the URL below is a tasty way for students to model plate interactions. With their models, students will see how the density, thickness, and pliability of plates affect how they interact at plate boundaries. Students can create drawings of the different interactions as an assessment.
Students commonly think that plate boundaries always fall at the edges of continents. Show them the map of 15 major plates at the URL below. Point out the continents and then point out where the plate boundaries fall. The interactive plate boundary map at the bottom of the Web page uses color-coding to identify the plate boundaries as convergent, divergent, or transform boundaries.
Reinforce and Review
Copy and distribute the lesson worksheets in the CK-12 Earth Science for Middle School Workbook. Ask students to complete the worksheets alone or in pairs to reinforce lesson content.
Lesson Review Questions
Have students answer the Review Questions listed at the end of the lesson in the FlexBook® student edition.
Check students’ mastery of the lesson with Lesson 6.4 Quiz in CK-12 Earth Science for Middle School Quizzes and Tests.
Points to Consider
On the map in the figure above, the arrows show the directions that the plates are going. The Atlantic has a mid-ocean ridge, where seafloor spreading is taking place. The Pacific Ocean has many deep-sea trenches, where subduction is taking place. What is the future of the Atlantic plate? What is the future of the Pacific plate?
Using your hands and words, explain to someone how plate tectonics works. Be sure you describe how continents drift and how seafloor spreading provides a mechanism for continental movement.
Now that you know about plate tectonics, where do you think would be a safe place to live if you wanted to avoid volcanic eruptions and earthquakes?