About These BC-ESP Curriculum Exercises
These exercises are designed to guide students in their own inquiry, investigating what is recorded by their seismograph. There are many excellent resources available for science education based on seismology (see Other Educational Seismology Resources). In developing this curriculum, we have borrowed from some, adapted from others, and developed some of our own. In the spirit of scientific inquiry, we hope that you will do the same, and that you and your students, as members of the BC-ESP, will consider part of your role to be investigators with us to help determine what does and doesn’t work in your particular educational environment. Our goal is for this curriculum to grow in a manner that will fit the various needs of different educational environments. Here we describe how we have implemented the BC-ESP in our college level course, which is an introductory geoscience course designed for prospective teachers (see Barnett et. al., 2005). We have used these same exercises in many K-12 classes, with modifications appropriate for age level and various schools’ educational environments, and we have found them to work well for a wide range of student ages.
1. Build Your Own Seismograph
We begin this curriculum experience with an inquiry-based exercise in which the students are asked to build a seismograph based on their own ideas regarding what it might take to create an instrument that records ground motion. The purpose of this exercise is to give them an opportunity to figure out for themselves what the design of a seismograph might entail. The students are given a variety of materials (such as, tape, straws, empty paper towel rolls, glue, rubber bands, springs, marbles, etc.) and are instructed to build an instrument that would detect motion. They are encouraged to think through this problem from first principles to determine what attributes a seismograph should have in order to detect motion.
2. Exploring What Your Seismograph Records
Having encouraged the students to think about what it takes to record earthquakes, we introduce them to what is recorded on their classroom seismograph by way of this next inquiry-based exercise. When students walk into their school and see the seismograph screen on the day of a very well-recorded earthquake, it is hard to miss that an earthquake was recorded (Figure 1). However, most of the time the screen shows much less dramatic vibrations, such as students walking near the seismograph, people slamming doors, large trucks passing by the building, and natural “non-earthquake” vibrations, such as wind. By observing the seismograph screen on a regular basis, the students can eventually learn to recognize when an earthquake has been recorded, and can learn a lot about the different types of earthquake signals they recorded.
|Figure 1: (Top Left) The great Sumatra earthquake of December 26, 2004 (magnitude 9.0) recorded by an AS1 seismograph operating in a classroom at Garfield Elementary School in Brighton, MA. (Top Right) The magnitude 7.6 earthquake in Pakistan that occurred on October 8, 2005 recorded by an AS1 seismograph operating at the “Living Lab” (a science program for K-5 students operated by the Westford, MA Public Schools). (Bottom) The magnitude 6.7 earthquake that occurred in Chile on April 30, 2006 recorded by an AS1 seismograph operating at Sea Lab (a science education center of the New Bedford, MA Public Schools). Although the signal from this earthquake is weak, it is definitely observable on the seismogram (dark arrow). Click on figure for larger view.|
To help them with this inquiry, we developed an exercise in which they are shown examples of earthquakes already recorded on AS1 seismographs, ranging from very dramatic (and hard to miss) recordings of earthquakes to very subtle ones that are hard to identify (Figure 1). With these examples as a guide, they are asked to identify different types of signals, to learn how to recognize the “fingerprints” of an earthquake on their seismograms, and to distinguish earthquake signals from other types of recorded vibrations. This exercise is later followed by more formal instruction on seismic wave propagation and the various types of waves that are generated by earthquakes.
3. Earthquake Tracking
This exercise was modeled after the epicenter plotting exercise described by L.W. Braile and S.J. Braile (2001), which provides a simple yet effective way for students to directly experience the concepts underlying earthquakes and plate tectonics. Each week, the students plot on a map of the Earth all earthquakes of magnitude ≥5.0 that occurred during that week. As the weeks progress, the students construct a cumulative plot that eventually includes earthquakes that occurred during an entire school year. They initially observe a distribution of epicenters that seems random, but after about a month, they see patterns developing, and the Pacific Ocean’s “Ring of Fire” begins to emerge from the scatter. By the end of a few months other plate boundaries begin to emerge (Figure 2).
|Figure 2: Earthquake tracking for one week (September 8-14, 2003), for one month (September 8 – October 7, 2003), and for four months (September 9 – December 7, 2003). Data are from the National Earthquake Information Center web site (neic.usgs.gov), and are for magnitude≥5.|
4. Recording Sensitivity of Your Seismograph for Earthquakes of Different Magnitudes and Distances
When a significant earthquake occurs, many of the BC-ESP students and teachers are curious to know (from the experts) if they recorded it, but they are often reluctant to think through the answer by themselves by analyzing the size of the earthquake, the distance of the earthquake from their school, and what earthquakes have previously been recorded at their school. To encourage them to think through this problem by themselves, the students are asked to make a plot of earthquakes recorded versus not recorded by their seismograph (see Figure 3). There should be a curve on that graph representing the threshold for how big an earthquake must be at a given distance in order for them to record it at their school. Figure 3 shows our results for an AS1 seismograph operating at Boston College. The students’ results will be similar, but not identical, to the results shown in Figure 3, because their site is different from the Boston College site (and their seismograph might be different). Once they have constructed a plot for their classroom seismograph like the one shown in Figure 3, they should be able to predict in advance whether an earthquake that has occurred somewhere in the world is big enough that it is likely to be recorded by their seismograph.
5. Locating Earthquake Epicenters
In this exercise, students are provided with several examples of earthquakes that were recorded at stations surrounding their epicenters, and for each earthquake they are given several seismograms and the location of their corresponding seismograph stations. Given this information, the students are asked to determine the epicenter of the earthquake that generated the seismograms. This exercise engages students in multiple scientific inquiry processes including analysis of data, reading and interpreting of data (seismograms), and conversations with their peers regarding their findings.
There is quite a variety of exercises available in which students are asked to locate earthquakes using seismograms, and most school curricula include some variation of this exercise (see Other Educational Seismology Resources). The challenge with these earthquake-location exercises is that, since P-waves and S-waves are usually not as easy to identify on seismograms as textbooks tend to suggest, the exercises often use either “fake” seismograms (drawn in textbook-simplicity style), or they might ask the students to search the Internet to find real seismograms themselves (and the seismograms they find often have P-waves and S-waves that are nearly impossible for non-seismologists to identify). The earthquake location exercises that work best are the ones that use real seismograms, but where seismologists have chosen examples where the P-waves and S-waves are relatively straightforward to read. That is what we try to do here. For this exercise, we have chosen examples that, while not one of the very rare cases that are so easy to read that they might as well be “fake”, are also not the all-too-typical cases that are so hard for the untrained person to read that the students are too frustrated to proceed with the exercise and locate the earthquake.
6. Scale Model of the Earth’s Interior
Life on Earth exists within the biosphere, a thin layer extending down into the Earth’s upper crust (generally in the upper few km) and up to about 10 km into the atmosphere. This thin layer of life is supported by the internal layers of the Earth and is surrounded by the vast expanse of space surrounding the Earth. As part of the BC-ESP curriculum, students study the interior of the Earth. This exercise is intended to give them a sense of the scales of different layers of the Earth, and the fact that the life forms that they are familar with exist within a very small layer near the surface. Another goal of this exercise is to teach students about the internal structure and composition of the Earth, and to help them to understand how scientists determine what the interior of the Earth is like (even though no one has ever been there).
This understanding of the internal structure of the Earth is important for teaching about what is recorded on the classroom seismographs because the paths of the seismic waves, which start at the earthquake and end at the seismograph, are distorted by the variations in internal structures within the Earth. Seismic waves are recorded at the surface of the Earth, and seismologists study the characteristics of seismograms to unravel clues about the earthquakes that generated those waves, as well the internal structures the waves have propagated through. By studying the waves recorded on seismograms, seismologists are able to infer what the Earth’s interior is like.
7. Earthquakes Within Reach: Classroom Mechanical Fault Model
This exercise was designed to help students understand the behavior of faults and the challenges of earthquake prediction. We leveraged an activity developed by Hall-Wallace (1998) to encourage students to investigate the mechanics of the so-called “stick-slip” behavior of faults. The experimental apparatus includes: blocks of wood that are placed on a flat board and connected to a bungee cord and a rope wrapped around a hand crank. The geological motion of “tectonic plates” is modeled by slowly turning the crank, and “earthquakes” are modeled as events in which the block slips. Fault friction is modeled by using different types of sandpaper between the blocks of wood and the board.
This exercise is open-ended, with multiple variables to be tested, including type of fault surface (fine, medium, or rough sandpaper), the mass of the blocks of wood, the elastic behavior of the bungee cord, and how fast energy is added to the system. This problem does not have a single “correct solution” and supports students in collecting data and analyzing the relationships between variables to investigate whether there are any variable relationships that might suggest how to predict the occurrence of earthquakes (or in this case “blockquakes”). The exercise ends with the students presenting their findings to one another, and during their presentations it becomes apparent that each group had collected a distinctive set of data and that to understand the results of the experiment will require additional discussion and re-checking of their own experiments.
8. Student Presentations
In our course at Boston College, we end the semester with asking the students to give presentations on how well these exercises work, and how to best use these exercises to encourage a culture of scientific inquiry in K-12 and college classrooms. While this particular form of student presentations may not be appropriate for K-12 students, we think that some kind of end-of-curriculum student presentations would be appropriate in many situations. Here is what we have our students present to the class at the end of the semester:
(1) Choose one of the lab exercises we did this semester, and describe aspects of the lab that worked well for teaching science, as well as what did not work so well and how you could improve the lab.
(2) Describe an additional lab that you think would be worth doing for this course. This can either be something that you developed yourself, or something that has already been developed by someone else that you think would work for this course. If you use something that was developed by someone else (such as something you found in a lab book or on the Internet) make sure that you reference it and give proper credit as to where it came from.
We encourage BC-ESP teachers to develop their own end-of-curriculum projects, and to have their students give presentations on some aspect of what they learned through these exercises.
We hope that you and your students will find the BC-ESP curriculum to be a rewarding learning experience. Remember that the BC-ESP is still a work in progress, and you are part of the team. After going through these exercises with your students, we hope that you will be inspired to try them again in future classes, to modify them to fit the needs of your school and your students, and to let us know what did and didn’t work well for your particular learning environment.
And, remember to keep looking for earthquakes recorded on your classroom seismograph!
Barnett, M., A.L. Kafka, A. Pfitzner-Gatling, and E. Syzmanski (2005), The Living Earth: Inviting Students Into the World of Scientific Research Through Seismology, Journal of College Science Teaching, 34(6), 50-54.
Hall-Wallace, M. (1998). Can Earthquakes be Predicted?, Journal of Geoscience Education, 46, 433-443.