Science Lesson: Here to There, Who Cares?

Abstract
In this lesson students will analyze the data they collected and the maps they have made to find “the missing pieces of the puzzle”, mantle convection. By the end of this lesson, students should have identified this missing piece by discussing the possible implications of moving plates on humans.

Purpose – Students will apply the evidence that supports Continental Drift and use it to question the theory itself.

Objectives
Students will be able to:
1. Orally identify that the force causing plate motion is missing from Alfred Wegener’s theory.
2. Orally identify a current geologic process that may hold the key to discovering the force moving the plates.

National Science Education Standard:
CONTENT STANDARD D: Earth and Space Science
The Origin And Evolution Of The Earth System
• Interactions among the solid earth, the oceans, the atmosphere, and organisms have resulted in the ongoing evolution of the earth system. We can observe some changes such as earthquakes and volcanic eruptions on a human time scale, but many processes such as mountain building and plate movements take place over hundreds of millions of years.

Teacher Background
Although Alfred Wegener and his colleagues were able to find evidence that supported the Continental Drift Theory, many scientists at that time were skeptical. Their biggest concern was the fact that their hypothesis left a major question unanswered. “If the plates were indeed moving as the theory suggested, then what geologic forces were strong enough to drive that motion?” As we now know, that force is mantle convection, which is driven by the heat of the Earth’s core. Hot magma rises from the depths of the mantle towards the crust. There it cools and sinks again.

Related and Resource Websites

Our Changing Continent
http://pubs.usgs.gov/gip/continents/index.html

Activity

1. Have students begin by summarizing the week’s findings. What do they now theorize happened to Earth in the last few hundred million years? How do they know?

2. Once students have given a detailed summary, ask the students “If Wegener’s theory is so complete, then why didn’t his colleagues accept it? What’s missing?” Students will probably sit quietly for a while and you may need to lead them through with questioning strategies. Ultimately, we want students to arrive at the conclusion that Wegener’s contemporaries did not accept his theory because he could not explain how the plates moved. (One analogy that might help students is to ask them “What would you say if I told you the sun was going to explode tomorrow?”)

3. Once students realize that the “how” was missing from Wegener’s theory, put them into their lab groups to brainstorm geologic processes that might give us clues. Some questions that might get them started are: What might a scientist look for to explain how South America separated from Africa? What might have caused India to move from the cost of Africa to Asia? What would show how Antarctica moved south? What physical features might give us clues?

4. Allow groups ten to fifteen minutes to debate this issue. Tell them they will have to select one representative to share their hypothesis before the end of class. . (If the class is finding this especially difficult, you might choose to do this as a whole group. Alternatively, you may want to draw students’ attention to earthquakes, volcanoes, and mountains to help get them on the right track. Another option is to have students visualize anything they can think of that appears to separate on its own. What causes it to separate? (Think leaves floating on water, etc.).

5. Record group hypotheses on a chart for use the next day.

Closure
Discuss the similarities and differences between hypotheses. What questions still linger? How could these ideas be tested? What further information might be of use to the students?

Embedded Assessment
Did students identify that the force driving plate tectonics is missing? Can they identify a current geologic process that may hold the key to discovering that force?

Homework
Write a 2-3 sentence conclusion in your science notebook. Conclusions should tell what you learned and be thought provoking.

Embedded Assessment