LESSON PLAN

Subjects: Earth Sciences

Grades: 7- 12

Concepts: analyzing data, graphing, predicting, modeling, and hypothesizing

National Content Standards:

1.  (A) Science as Inquiry Develop descriptions, explanations, predictions, and models using evidence.

2.  (A) Science as Inquiry Thinking critically and logically to make the relationship between evidence and explanations.

3.  (A) Science as Inquiry Use mathematics in all aspects of scientific inquiry.

4.  (B) Physical Science Transfer of energy via mechanical motion.

5.  (D) Earth and Space Science Structure of the Earth system - The solid earth is layered with a lithosphere; hot, convecting mantle; and dense, metallic core.

6.  (E) Science and Technology Understandings about science and technology - Science and technology are reciprocal.

7.  (F) Science in Personal and Social Perspectives Natural hazards - Internal and external processes of the earth system cause natural hazards, events that change or destroy human and wildlife habitats, damage property, and harm or kill humans.

8.  (F) Science in Personal and Social Perspectives Risks and benefits

9.  (F) Science in Personal and Social Perspectives Science and technology in society

10. (G) History and Nature of Science Nature of science - It is part of scientific inquiry to evaluate the results of scientific investigations, experiments, observations, theoretical models, and the explanations proposed by other scientists.

11. (G) History and Nature of Science History of science - Tracing the history of science can show how difficult it was for scientific innovators to break through the accepted ideas of their time to reach the conclusions that we currently take for granted.

Duration: Eleven 50-minute sessions or five 50-minute and three 90-minute sessions.

Introduction

Earthquakes are one of the most powerful natural forces that can disrupt our daily lives. Through careful study, geologists are slowly learning more about such questions as these:

Can earthquakes be predicted?
Can we design a city to better withstand an earthquake?
Can we stop earthquakes before they occur? Should we try?

Students assume the role of a seismologist while working on several self-guided activities to help them think like a geologist.  Some of the activities depend on material learned form previous activities; therefore, completing the activities in order will help students to understand each activities better.  After developing an understanding of how seismologists collect and analyze data and how earthquake epicenters are located, students

Objectives

Students will...

1. demonstrate an understanding about the three types of earthquake stress that occur in the crust and associated fault deformations.

2. distinguish between the three categories of seismic waves.

3. analyze and interpret data to locate the epicenter of an earthquake.

4. draw conclusions about the inside of the earth.

5. develop a model of the earth and evaluate the model for its strength and weaknesses.

6. think critically about scientists role in society.

Background Information

Seismosurfing:  Students print out a scavenger hunt worksheet.  By accessing a variety of listed websites, students are capable of completing the scavenger hunt.  Students will learn that searching results in a strike-slip fault, tension results in a normal fault, and that compression results in a reverse fault.  Students will also develop an understanding of how P (primary), S(secondary), and L(long or last) waves travel.

Answers to the crossword puzzle can be found here: Earthquake Crossword Answer

Suggestions:

Since an understanding of this information is important background information for the other activities, encourage students to utilize a dictionary or the definitions link.

Reading a Quake:  Students will view simplified versions of eight seismograms from eight locations around the world. All eight seismograms were caused by the same earthquake, though the epicenter of this quake is not revealed (students discover it in the later activity Locating an Epicenter) Students will answer questions regarding these seismograms. Questions focus on identifying the three main types of seismic waves (P, S, and L), observing that not all cities received all three wave types, and beginning to hypothesize why some cities did not get all of the waves.

Suggestions:
Students will probably need help understanding the seismograms. Make sure they clearly understand these points:
1) All recorded waves for all eight locations came from one earthquake (the quake originated in the Asian side of the Pacific Ocean).
2) Although the seismic waves that created the zig-zag lines left the epicenter at exactly the same moment, they arrived at different times in different locations. Cities that were close to the epicenter received waves first; distant cities received waves last.
3) The first wave to arrive is always the Primary (P) wave, (unless the P wave is deflected and never arrives at all).
4) Each city started recording its seismogram at the exact moment the P wave first arrived there. Thus each city started recording at a time of day different from any of the other cities.
For example, if the quake began at 12:00 p.m., Tokyo received the first P waves at about 12:05 (and the first S waves at about 12:09), but Rio received these same P waves at about 12:20. (In this activity, students can determine for themselves which cities are nearest the epicenter.)
What should the student learn in this activity?
The earthquake created at least three types of waves:
1) A first wave (Primary, P) that hit suddenly but with only minor vibrations, and then slowly died out.
2) A second sudden set of small vibrations (Secondary, S) that slowly died out.
3) A final set of very large vibrations (Last, L) that pulsated by growing larger, then smaller, then larger, etc.
Students should also learn that some cities which are relatively near each other (compared to the size of the earth) receive very different waves. One city can receive P, S, and L waves, while a nearby city receives only L waves.
Encourage students to hypothesize why some waves do not show up at certain locations. This answer is found in the layers of the earth's interior, as students will find out if they complete Disappearing Waves. Something inside the earth is interfering with the waves that are trying to reach all part of the globe. (If students locate the cities on a map, they may speculate that the oceans cause the wave loss, since liquids always stop S waves. However, P and S waves travel easily through the rock underneath the oceans, and so the oceans are not the cause of the wave loss.)

Locating an Epicenter:  Students study three seismograms from three different seismic stations (Tokyo, Sydney, and Hawaii) to determine how far away from the epicenter each one is located. Then students plot these three cities on a map of the Pacific Ocean region, draw a circle around each city representing how far away the epicenter must be, and identify the point on the map where all three circles roughly intersect -- the epicenter.

Suggestions:
Students may need a lot of guidance on the questions of this activity, but the process of discovering the location of the epicenter can be interesting.  The first part of the activity is simply determining the distance from Tokyo, Sydney, and Hawaii to the actual epicenter of the unknown earthquake. (This is the same earthquake that created the seismograms in Can You Read a Quake?, so this activity refers back to the same seismograms.)  In this first part, students should confirm that Tokyo is roughly 3100 km away, and then they should determine that Sydney is roughly 4900 km away and Hawaii is roughly 8600 km away.
The second part of the activity is locating the epicenter on the map. Show students how to understand and use the kilometer (or mile) scale on the Pacific Ocean Map. One way is simply to measure the given map scale in centimeters and then use this measurement as a ratio. For example, if 1000 kilometers on the map is equivalent to 2 centimeters on the ruler, then Tokyo is...
      If Map = 1000km, Ruler = 2.0 cm
      If Map = 3100 km, Ruler = 6.2 cm
In this example, students would need to draw a circle of radius 6.2 cm around Tokyo. (These calculations are not explained in the activity.)  Students should repeat the same circle-drawing process for Sydney and Hawaii, being careful that in each case they use the seismogram specific to that city. (If Tokyo has a P to S time delay of 4.2 minutes and thus is 3100 km away from the epicenter, its circle on the example map is 6.2 cm in radius. Sydney would have a larger time delay and thus a larger distance and a larger circle.)
Once they have accurately drawn all three circles, most students will find that the three circles do not meet exactly in one point but rather form a small triangle. The epicenter is somewhere inside of this triangle -- near the Philippines.

Early Earth:  Students explore what early scientists and philosophers thought the inside of the earth looked like.

Suggestions:

Explore with students the difference between a scientist and a philosopher.

Disappearing Waves:  Students are asked to hypothesize why some seismic waves disappear on their way through the interior of the earth. In the process of answering this question, they will step through a series of clues from seismic waves to determine and draw how the inside of the earth is layered.

Suggestions:
This lesson has several diagrams of the interior of the earth. Some of these diagrams are simple; others may need some helpful interpretation by the teacher.   Students will mostly be reading and studying diagrams.  The teacher could prepare several overhead transparencies of the wave diagrams.  Overlaying these transparencies on the overhead gives students a great visual of circular layers inside the Earth.

Drawing Earth:  After analyzing the clues from seismic waves in the previous activity, students demonstrate their understanding of how the inside of the earth is layered.  Students can either draw a picture or think of a model that resembles the earth. 

Suggestions:

The student drawings of the interior need not be complicated. They should simply show round (spherical) layering at the five specific depths shown in the P wave reflection diagram.  Students can color in each layer, identify which layers are solid, and then explain with their diagram why S waves have a shadow zone and why P waves have a shadow zone. The S waves are completely stopped at 2900 km by the molten iron/nickel outer core. The P waves that try to glance through the outer core at an angle are deflected toward the center of the earth at this depth and so they never arrive at the shadow zone region.

Students could be asked to evaluate their drawing or model for its strengths and weaknesses.

Hazards and Safety:  Students read about how and the kinds of damage earthquakes cause.  They also focus on what can be done to reduce earthquake hazards.

Suggestions:
Have students practice the technique of "echo reading."  The teacher reads a sentence or portion of a sentence aloud and then students repeat or echo what the teacher has read.  Students should follow along with the teacher.  After reading a section of the material, students close the reading material and answer questions that focus on their comprehension of the material just read.

Tomorrows Earthquakes:  Students are asked to consider some of the more difficult issues regarding predicting and preventing earthquakes.

Suggestions:
This activity can be assigned in several ways:
1) Individual students write their own responses to the issues presented.
2) An individual or a group of students is assigned one of the geologic teams and gives an oral presentation to the class.
3) The class is divided into four groups. Groups A and B debate the Prediction Team issue, and groups C and D debate the Prevention Team issues.

More to Learn:  This site has not yet been completed.

Suggestions:

Materials

• Computer with internet access

• Journal printout

• Pens/Pencils

• Circle drawing compass

• Pens/Pencils

Procedure

1. Introduction:

In the beginning of the excursion, students will complete an internet scavenger hunt by linking to several websites.   Either hand out or have students print the scavenger hunt worksheet.  Students access the student Seismosurfing site on the internet webpage.

2. Excursion:

Students follow the procedures set up in the process section of the webpage.  They begin with TASK 1 and continue in order until all activities are completed.

3. Explanations:

Facilitate student achievement by reviewing their work throughout the lesson.  Utilize the background information to ensure that students are learning and performing the excursions accurately.  Frequently ask individual students or cooperative learning groups questions that access their understanding.

4. Connections:

The lessons Reading the Quake and Locating an Epicenter require students to use mathematics skills.  The What should be done about tomorrows earthquakes activity asks students to write a one paragraph position paper.

Closing (Applications)

1. Students apply their understanding of seismographs to locating the epicenter of an earthquake.  They explore how this information is helpful in determining possible patterns to earthquake locations by plotting the location of epicenters on a model globe.

2. Students discuss what else earthquakes could tell scientists.

3. Students apply what they have learned about earthquake damage and safety to analyze the risks and benefits of issuing earthquake predictions with 10% accuracy or preventing large scale earthquakes by creating smaller ones.

Assessment

The internet lesson assessment rubric is given as a suggestion to use in evaluating students and may be printed separately.

Sources

Dixon, Dougal.  The Practical Geologist.  Simon & Schuster Inc. New York.

Earthquake! [web site]. Available from http://cse.ssl.berkeley.edu/lessons/indiv/davis/hs/QuakesEng3.html.  Accessed August 2002.

National Science teachers Association. Project Earth Science: Geology. NSTA.  Virginia.

Simons, Barbara  Brooks. Science Explorer: Inside Earth. Prentice Hall. New Jersey.