Plate Tectonics Activity
Here is a fascinating activity that will help you give your students a better understanding of Earth's structure and how it creates tectonic plate movement. This activity is designed for students in grades 5–8.
How do you help your students visualize the huge convection cells of solid material circulating within Earth's mantle that create tectonic plate movement? This activity offers a solution: Create miniature convection cells within a desktop flow chamber so that students can see firsthand how convection cells are created and how they work. The key then to explaining how convection cells drive plate tectonics is to keep it simple. There is a vast amount of information about Earth's interior structure, all interesting, but not critical for an understanding of basic plate tectonics.
Students may question why the hottest part of Earth, the inner core, is solid, and why the outer core, which is cooler, is liquid. Here is the answer. The immense pressure at the inner core causes it to remain solid even though it is hotter. The outer core is under less pressure so it remains liquid even though it is cooler.
Here are the basics. A cross section of Earth would reveal 3 major internal structures: the core, mantle, and crust. The core is made of 2 distinct regions, the inner core and outer core. The inner core is solid, and the outer core is liquid (see "Teacher's note"). For this activity, consider the core as one area located in the center of Earth producing vast amounts of heat. The mantle, an area of slowly moving convection cells of solid material between the core and the crust, is divided into several regions based on temperature and plasticity. For this activity, consider the mantle as a single contiguous region between the core and the crust where convection cells form.
The crust consists of 2 parts, the oceanic crust and the continental crust. The oceanic crust is the lower layer. It is made of basalt, a very dense, heavy material that is actually magma solidified by contact with cold seawater. All Earth's seafloors are made of basalt. The second part of the crust is the upper layer or continental crust. Less dense and lighter than the oceanic crust, it makes up Earth's continents. The oceanic and continental crusts are also known as the oceanic and continental plates or generically as tectonic plates.
Now, let's put it all together. Heat from the core creates convection cells within the mantle. The tops of these convection cells function like conveyor belts, slowly moving Earth's tectonic plates. This movement is the key concept in the theory of plate tectonics.
- Rheoscopic fluid
- French square bottle
- Ring stand
- Incandescent desk lamp with 75-W bulb
Safety note: If you decide to use your own French square bottle, make sure it is made of clear glass. Do not use a plastic bottle.
- Shake the bottle of rheoscopic fluid to ensure it is thoroughly mixed.
- Fill the French square bottle completely with rheoscopic fluid, being careful not to leave any pockets of air. Screw the cap on tightly.
- Place the bottle on the ring stand as shown in figure 1.
- Place the lamp directly under the center of the bottle as shown in figure 1.
Do not turn on the lamp.
Figure 1. Rheoscopic fluid flow chamber set up.
- Begin by asking the class to share what they know about Earth's structure. Here are some suggested questions:
- How thick is Earth's crust?
- What is under Earth's crust?
- What is the inside of Earth like?
Final discussion questions
Lead your students through these questions. Have them refer to their notes if necessary.
- Q. What is at the center of Earth?
A. A heat-producing core.
- Q. What is the mantle?
A. An area of solid material surrounding the core.
- Q. What is formed in the mantle as a result of the heat from the
A. Convection cells.
- Q. What are tectonic plates?
A. Portions of Earth's crust that are moving in various directions at various rates
- Q. What part do convection cells play in the movement of tectonic
A. They act as conveyor belts, pushing and pulling the plates.