Earthquakes (Day 2/2)
Lesson 7 of 16
Objective: SWBAT define an earthquake, locate an earthquake's epicenter and analyze the intensity of an earthquake as a function of its seismic wave amplitude
This lesson is a continuation of yesterday's lesson (also attached above as an entire lesson - previous day's link here). This is an introductory lab focusing on earthquake and projected damage as measured by the Mercalli Scale. Students use a simulated earthquake in concert with damage reports to identify the Mercalli Intensity at various locations at a distance from the epicenter, and today allows them to finish their labs in their collective lab groups, do some post-procedural analysis, and create some isolines delineating zones of damage. Additionally, for the first time (but not the last time), they're going to be introduced to the term isolines. Isolines are lines that connect other points of equal value. So if one were to connect all elevations on a landscape with an elevation of 800 feet, an isoline would be used. In this lab, they are going to be used to identify all points with the same amount of earthquake damage. Finally, there are special materials and preparation needed for this lesson, which are posted in the Lab Introduction section below (they are also posted here).
- Earthquake Scenario Cards (One per lab group - printed out, cut, and placed into envelopes)[May also want to laminate for future use]
- Mercalli Scale (One per person)
- Mercalli Scale Map (One per person)
[Note: For additional information, including embedded checks for understanding and teacher directions, refer to the 2.6 - Introduction To Earthquakes (Whole lesson w/comments), or the PDF version of the lesson here: 2.6 - Introduction To Earthquakes (Whole lesson).]
Since this is a continuation of yesterday's laboratory assignment, there is no established 'Do Now'. When students come in, they take their seats, and I usually start with a probing review question or two from yesterday (i.e. "So yesterday, we learned about earthquakes. Can someone tell me how earthquakes happen?" or "How are earthquakes measured?"). Then, as always, I time their transitions from their normal classroom arrangements into the laboratory groups. Then, once they receive the Earthquake Scenario Cards, they can re-start their lab where they left off.
Mercalli Scale Lab
In this section, they get some serious work time to go through and diagram all their Mercalli Scale Pieces on their Mercalli Scale Map. What this means specifically is that they need to go through each of the Earthquake Scenario Cards and figure out the precise location they're talking about on the Mercalli Scale Map. As an example, using Card 1, the first line indicates that the caller is "from the hospital." Then, students can find the Hospital on the Mercalli Scale Map, and use the Mercalli Scale to determine the relative damage that occurred at the hospital based on context clues (feel free to use the provided Earthquake Scenario Key to help out with this, or to use while you're circulating with students to check their work in real time).
When students determine the appropriate Mercalli Scale intensity using the Mercalli Scale, they should place the intensity value (in Roman numerals) directly on the Mercalli Scale Map. When finished with all the cards, each location on the map should have an associated Mercalli Scale intensity attached to it.
In terms of the actual Earthquake Scenario Cards, they absolutely do not have to be done in any specific order, as there is one scenario card per location on the Mercalli Scale Map. As long as all students in the lab group attach a Roman numeral value to each location, the specific order or sequence isn't important. While they're doing this, I'm generally circulating amongst the laboratory groups in question, making sure they're keeping up with time and that they're understanding the procedural steps of the assignment.
Once they have the Mercalli Scale intensity identified for each of the respective locations, I have them discuss the question - "Can you pinpoint the epicenter based on the Mercalli Intensities?" The answer - once students have them all diagrammed and can view them - is that the intensities increase as they approach certain sections on the map. The Mercalli scale intensity directly increases as you approach the epicenter - this can be delineated clearly on the Map Key (Note: You can also use the Earthquake Scenario Key to help students if they're stuck).
Once we discuss the specific intensities for each location and students are able to clearly see a pattern of increasing intensity with decreasing epicenter distance, I quickly use the document camera to share the key with them and go over each of the sites and relay the correct Mercalli intensity. I then model for them how to do something that they'll a see a few more times in the Earth Science curriculum - we create isolines of similar Mercalli Intensities.
Isolines are used often in weather maps (something we definitely visit later on in the course), but they're introduced here as a way to connect points of an equal value on a map or chart. I model drawing isolines for the lower Mercalli intensities, and then instruct the class to do the same on each of their respective maps. The best way to describe it is as a primitive game of connect the dots. Starting from the lowest intensity, you will make gradually smaller circles as you connect all the points with the same Mercalli intensity (Note: Isolines never cross). As they get closer to the epicenter, the concentric circles get smaller as they hone in on the epicenter's location. Once they have the isolines completed, the highest Mercalli Scale intensity has a relatively small circle around it. I then ask students to put an 'X' somewhere in that small circle, as that is the most likely location of the earthquake's epicenter. After that, I have students transition to the exit ticket.
Exit Ticket & Closing
Students get started on the Exit Ticket as soon as they're finished completing the isolines on their earthquake intensity maps. The reason that an exit ticket is given here is that I really want them to see multiple choice variants of the skill they've been working with the past two days - recognizing Mercalli Intensity maps (and isolines) as well as other essential information on earthquakes.
Students are given about three (3) minutes to quietly work on the exit ticket, after which I usually do a "trade and grade" or have students grade their own work. Once the exit tickets are scored and scores are reported (students also keep an "Exit Ticket Tracker" to keep track of all of their exit tickets in a unit) in their trackers, they are asked to pack up, transition back into the normal classroom arrangement from their lab groups, and get ready to leave. During the last minute or so, I go over to the objective at the front of the room and ask 1-2 students for feedback on the lab, and to self-report if they mastered the objective (they usually respond by reporting their exit ticket scores). After the bell rings, students transition out of the room once they're dismissed.