I love teaching the theory of plate tectonics because I love it when history and science overlap. First, it allows us to tell a story, and we learn best with stories. Second, it is an opportunity to show our students the scientific process in action.
The Story of Plate Tectonics
The story of plate tectonics started over 100 years ago. Alfred Wegener was a German meteorologist and geophysicist. One day, around 1912, while looking at maps, he noticed that the continents’ outlines looked like they fit together like puzzle pieces. He also discovered that similar fossils were found on continents separated by oceans, and Antarctica had fossils of tropical plants buried beneath the snow.
Based on his discoveries, Wegener believed that the continents were once joined together in a supercontinent he called Pangaea. For some reason, the continents broke apart and moved to their current locations. Wegener didn’t have a mechanism to explain how the continents moved, but he called his theory continental drift.
Scientists of the day ridiculed Wegener and his theory. They couldn’t imagine how something as big as a continent could move. Unfortunately, Wegener died on an expedition before the genius of his ideas was realized.
The evolution of the theory of plate tectonics is a perfect example of the relationship between science and technology. In 1912, scientists didn’t have the tools they needed to study the continents’ movement, so they didn’t believe the continents could move. After World War II, new technologies changed everything.
Technology and Science
Seismometers measure earthquake waves. Working with seismometers, scientists realized that earthquakes didn’t happen everywhere on Earth. Instead, they repeatedly struck in specific locations. Furthermore, studying the ocean floor with magnetometers showed magnetic striping in the rocks. Scientists began to wonder why earthquakes only happen in certain locations and why the polarization of rocks flipped back and forth along the seafloor?
These questions and further research led to the development of the theory of plate tectonics based on Wegener’s earlier theory of continental drift.
Evidence suggests that the Earth’s lithosphere is made up of between twelve and twenty rigid tectonic plates. These plates float on the softer rock of the asthenosphere. Hot rock in the mantle flows very slowly in giant convection currents driven by the heat out of Earth’s core. Hot rock pushes its way through the lithosphere at spreading centers such as the mid-ocean ridges. When it cools, new rock forms. The new rock aligns with the magnetic field of the Earth. The Earth’s magnetic field flips about every 100,000 years, explaining the ocean floor’s magnetic striping.
The spreading centers push the plates around it apart. We call these places divergent plate boundaries. Plates collide at convergent plate boundaries. Oceanic crust is denser than continental crust, so when these plates collide, the oceanic crust is subducted under the continental crust creating a subduction zone. If two continental crusts collide, they fold up against each other and create a mountain range, like the Himalayas.
Teaching Plate Tectonics
You already know Alfred Wegener’s story and the evidence for plate tectonics; what you want to know is how to teach it to your students. As I said before, I love teaching with stories. Our brains are primed to learn from stories. We have been doing it for hundreds of thousands of years. You can tell your students the story, or you can show them a video.
SciShow is my favorite YouTube channel for learning about science topics. They do a great job of making complicated topics fun and interesting.
I also like to give students the opportunity to read about science topics. Reading during science is important for several reasons. First, students can always refer back to a reading passage if they need to answer a question or remember a fact. Second, reading is the primary way we learn new information in school so that the more practice students can get learning from reading, the better for their future academic goals. Third, it is easy to share information in a reading passage. You don’t need special equipment, and it is inexpensive. Fourth, students can annotate reading passages. It is not easy to annotate a video or a presentation. Fifth, students are actively engaged when they are reading, and they can work at their own pace. I could go on and on. There are so many reasons to use reading passages or information texts in your science classroom!
My reading passage on plate tectonics is so much more than just a reading passage with comprehension questions. You also get scaffolded note pages to help students record what they learned. Even college students struggle with taking notes. People write too much or write too little. The truth is, when you are learning something new, you don’t know what is important. Scaffolded notes help guide students to the key points on the topic. You also get vocabulary flashcards because science is vocabulary. Plus, a picture book to support struggling readers. Click on the image below to see everything included in the reading passage set.
Flashcards on Plate Tectonics
Once your students learn about plate tectonics, you want to help them remember what they learn. My favorite way to memorize information is flashcards. Flashcards are the perfect memorization tool. You can read all about why they are so helpful in my blog post on using flashcards.
Are You Teaching Another Science Topic?
I am working on creating more science units so that every science teacher can get exactly what he or she needs for her students. You can also read about how I use brain science to teach other science topics on my blog. Click the pictures below to learn more.