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Moving Continents: Plate Tectonics
How can something as solid as the ground beneath your feet actually move?

The ground beneath your feet isn't as solid and still as it seems. Earth's crust is broken into giant puzzle pieces called tectonic plates, and they're slowly moving. They create mountains, cause earthquakes, and even shift where continents sit. This lesson brings one of Earth's biggest stories to life: how Pangea split apart, how plates collide and slide, and why the world keeps changing.

S2S_Lesson07 by Selene

Key Ideas

  • The crust is broken into tectonic plates floating on the semi-fluid mantle.
  • Plate boundaries include divergent (moving apart), convergent (colliding), and transform (sliding past).
  • Plate movements cause earthquakes, volcanoes, mountain building, and ocean trenches.
  • Long ago, the continents were joined together in a supercontinent called Pangea and slowly moved apart.
  • The theory of continental drift explains how continents have moved over millions of years.

Spines
  • DK's Science as You've Never Seen it Before: pg. 124-125
  • Mammoth Science: Plate Tectonics pg. 136

✏️  Notebooking Activity
Label the diagram to show what happens at each of the three types of plate boundaries (convergent, divergent, and transform).

Cosmic CalendarWhere we are: Late September*
We remain in late September. Plate tectonics is an ongoing process rather than a single event, so this date is a reasoned estimate. Read the script below before the lesson.

Read aloud: We’re still in late September on our Cosmic Calendar. Earth exists now, and it’s not sitting still. Plate tectonics is not a single event with a single date. The movement of Earth’s crust has been going on since the planet was young, and it never stopped. So our marker today stays in late September to represent this ongoing, slow process that began billions of years ago and is still reshaping our planet right now. One important thing to keep in mind as you look at this calendar: we’ve been in September for several lessons now, and we’re not going anywhere new for a little while. That’s on purpose. A huge amount of Earth’s story takes place before we ever get to December. Be patient with September. It matters.

Timeline PageLabel the next page in your timeline “Pangea Forms: 335 Million Years Ago”. The workbook prompt asks learners to draw all of Earth’s continents pushed together into one giant supercontinent with the ocean surrounding it.

Discussion Questions
  • What was Pangea? 
    Sample answer: It was a "supercontinent" from a long time ago when all the land on Earth was stuck together like one giant puzzle.
  • If the continents were once one piece, how did they get where they are now? 
    Sample answer: They are sitting on top of giant plates that slowly drifted apart over millions of years.
  • How do we know the continents used to be joined together? 
    Sample answer: Because the shapes of the continents look like they fit together, and we find the same fossils on different sides of the ocean.
  • Describe the three main types of plate boundaries. 
    Sample answer: Divergent (plates pulling apart), Convergent (plates crashing together), and Transform (plates sliding horizontally past each other).
  • What happens when two continental plates collide at a convergent boundary? 
    Sample answer: Neither plate is dense enough to sink, so the crust crumples and folds upward, creating massive mountain ranges like the Himalayas.

Digging Deeper

  • How does the theory of Continental Drift explain the current layout of our map? 
    Sample answer: It suggests that the continents were once a single landmass (Pangea) that broke apart and drifted to their current positions over millions of years.

SCIENTIST SPOTLIGHT: Marie TharpMarie Tharp was a geologist and cartographer who created the first scientific map of the entire ocean floor. Despite being barred from research ships due to her gender, Tharp used sonar data to reveal that the seafloor was not flat but filled with mountains and valleys. Learners can explore the Mid-Atlantic Ridge and understand how Tharp’s work provided the "smoking gun" for the theory of plate tectonics.

Videos: 
Books:Digging Deeper
How did Tharp translate sonar readings into a visual map by hand? What obstacles did she face as a woman in mid-20th-century science? Write a short biography entry for her from the perspective of a future encyclopedia.

Sources

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