Earth & Space Science: Session 3
Lesson and Curriculum
at a Glance:
Curriculum: Activity designed by Keedar Whittle
(download the lesson plan as an Adobe PDF document)
Topic: Earth’s Interior
Keedar’s lesson featured three activities that illustrate the nature of the Earth’s mantle. The first used Slinkys® to simulate the wave movement caused by earthquakes. Keedar has students tie one end of a slinky to a table or chair leg and then has them simulate the two types of waves created at the epicenter of an earthquake. Compression waves, or primary waves (P waves), are simulated when the students stretch the Slinky® out on the floor, and push one end straight toward the other end. Compression waves are “primary” because they are faster than shear waves, or secondary waves (S waves). The motion of a shear wave is simulated by moving one end of the Slinky® back and forth perpendicular to the other end. In addition to having the students simulate both waves, Keedar had them time the waves, to see if they could detect which is faster.
The other activity involved Silly Putty®, which has qualities of both a liquid and a solid. Keedar illustrated this point by having his students roll the putty into a ball, place it on an index card, and, with a pencil, trace the outline of the ball. When the students checked on the putty 30 minutes later, they found that it had spread beyond the outline they had made, apparently through the force of gravity alone.
Finally, Keedar illustrated convection currents with a specially designed milky-white colored fluid that shows the currents when it’s heated. All three demonstrations provide students with insight into what is otherwise a wholly inaccessible place — the Earth’s mantle. The demonstrations, Keedar feels, will leave his students with a lasting impression of how the Earth’s interior functions. “Students may forget certain definitions, and that’s okay. What I would like is for them to be able to broadly explain plate movements and interactions down the road.”
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