8.2.3.1 Waves
Explain how seismic waves transfer energy through the layers of the Earth and across its surface.
Overview
MN Standard in lay terms:
Most waves require a medium to move through. The medium may be a solid, liquid or gas. The wave is a disturbance that causes the particles that make up the medium to vibrate. This vibration represents energy of motion and it passes through the medium as particles transfer their energy of motion to other particles.
Big Idea:
Waves are disturbances that travel through space and time. Waves travel through a medium and their motion transfers energy along the path of the wave with no transfer of the particles in the medium. Think of a bobber floating on the water. It rises and falls as waves move through the water, but the bobber does not move with the wave.
The Earth Science Literacy Principles is a literacy initiative that represents the big ideas of earth science that all citizens should know. This standard connects with Big Idea 1. Earth scientists use repeatable observations and testable ideas to understand and explain our planet. Specifically, point 1.4 states that earth scientists must use indirect methods to examine and understand the structure, composition, and dynamics of Earth's interior. With the exception of wells and mine shafts drilled into Earth, direct observations of Earth's interior are not possible. Instead, Earth scientists observe the interior of the planet using seismic waves, gravity, magnetic fields, radar, sonar, and laboratory experiments on the behavior of materials at high pressures and temperatures.
- NSES Standards:
Content Standard B: Physical Science
Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways.
- AAAS Atlas:
- Benchmarks of Science Literacy:
The Physical Setting: E. Energy Transformations
Whenever energy appears in one place, it must have disappeared from another. Whenever energy is lost from somewhere, it must have gone somewhere else. Sometimes when energy appears to be lost, it actually has been transferred to a system that is so large that the effect of the transferred energy is imperceptible. 4E/M1*
Energy can be transferred from one system to another (or from a system to its environment) in different ways: 1) thermally, when a warmer object is in contact with a cooler one; 2) mechanically, when two objects push or pull on each other over a distance; 3) electrically, when an electrical source such as a battery or generator is connected in a complete circuit to an electrical device; or 4) by electromagnetic waves. 4E/M2*
Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves. 4E/M4*
Common Core Standards (i.e. connections with Math, Social Studies or Language Arts Standards):
English/Language Arts
Minnesota's newly revised (2010) English Language Arts (ELA) standards set K-12requirements not only for ELA but also for literacy in history/social studies, science and technical subjects.
6.13.4.4 Determine the meaning of symbols, equations, graphical representations, tabular representations, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 6-8 texts and topics.
6.13.7.7 Compare and integrate quantitative or technical information expressed in words in a text with a version of that information expressed visually (e.g., in a flowchart, diagram, model, graph, table, map).
6.13.8.8 Distinguish among claims, evidence, reasoning, facts, and reasoned judgment based on research findings, and speculation in a text.
6.13.9.9 Compare and contrast the information gained from experiments, simulations, video, or multimedia sources with that gained from reading a text on the same topic.
In conducting investigations on waves in the lab or by working with simulations, students will need to be able to interpret and support their findings through the use of content-specific language and representations (graphs, tables, etc.) of the data that they have collected. They will need to also use these tools to evaluate the data and information of others, including that found in related texts.
Minnesota Academic Standards in History and Social Studies (2004)
Geography VC2 : 2. Students will describe natural hazards, the physical processes behind them, the areas where they occur, and the costs and benefits of methods people use to mitigate their damage
Geography VD2 : 2. Students will analyze how the physical environment influences human activities.
In researching different seismic events that take place on the earth, students need to appreciate and understand variables that cause the event to be a disaster on one area and an inconvenience in another.
Misconceptions
This list is part of a comprehensive list of earth science misconceptions compiled by Kent Kirkby. This list was compiled by participants at a 2008 meeting of the National association of Geoscience Teachers (NAGT) at Carleton College. The larger list may be accessed here at the Science Educator Resource Center (SERC) website.
- Seismic waves involve the long distance net motion of particles
- Seismic waves go from crust to core, but not core to crust (textbooks seldom specifically discuss second half of journey apart from a general treatment of shadow zones).
- S-waves (shear waves) do not reach other side of Earth from where earthquake originated because they cannot pass through oceans (or cannot reach islands).
- Wind blowing through subterranean passages causes earthquakes (Aristotle's hypothesis, tied with older cosmology of hollow passages through earth)
- Earthquakes occur from collapse of subterranean hollow spaces (tie to older cosmologies).
- The biggest earthquake is a magnitude 10.
Other misconceptions that researchers find common to general wave behavior and properties which are applicable to this standard are summarized here as a part of Comprehensive Conceptual Curriculum for Physics (C3P). C3P was a professional development effort run through the University of Dallas.
- Waves transport matter.
- There must be a medium for a wave to travel through.
- Waves do not have energy.
- All waves travel the same way.
- Big waves travel faster than small waves in the same medium.
Vignette
The standard in action with a student-centered classroom
Students in Mr. S's Earth science class watched the video in wide-eyed silence as the tsunami rolled into the shore of the Tohoku region of Japan and enveloped everything in its midst. As Mr. S. flipped on the lights, the students remained quiet until he interrupted the silence with a question. "So, what caused the tsunami?" "The earthquake" offered Kendra. "But there are earthquakes all the time" said Nic. "Why do they hardly ever cause tsunamis?" "That's a great question, Nic", said Mr. S. "Let's think for a minute. What is a tsunami?" After a short silence, Jocelyn quietly said, "It's a wave". "Exactly!", exclaimed Mr. S. "What do you know about waves? Where would you go if you wanted to see waves?" Students looked at one another, some shrugging their shoulders. Mr. S. scanned the room and said, "Grab a white board. Take a few minutes with your group and jot down what you know about waves and what kind of things are waves. Let's gather back in 10 minutes."
"What do you have to share?", asked Mr. S. at the end of the allotted time. "Waves can be big or small", offered Jocelyn. "Waves can be caused by wind, and can be on a lake or ocean", said Taylor. "Earthquake waves can travel through the ground" shared Nicole. Grant then added, " My group said that sound travels in waves." "Good thoughts!" boomed Mr. S. "Strange that you should bring up sound...." From behind the desk, Mr. S. pulled out a box full of kazoos. "All right - this may be one of the crazier things that I have done in my teaching career, but I would like all of you to take a a kazoo and see what you can do with it in the next 5 minutes. You may keep your kazoos, but they have to be quiet when I call time. I want you to be able to tell me how the kazoo works at the end of that 5 minutes.
A short time later, Mr. S. raised his hands to cut off the cacophony of kazoo music and waited while students tucked them away in bags and pockets. "So, how does it work?" "Well, you just blow on it and it makes the little paper thing in it vibrate", explained Jarett. "Jarett, tell me what that has to do with waves", probed Mr. S. "I don't know... I guess when the paper vibrates, it is kind of like a wave." "What happens if you blow harder?" "The sound is louder", interjected Jordan. Monte excitedly interrupted, "Wait - I think I know. The harder you blow on the kazoo, the more energy it takes and the louder the sound gets. When we watched the video, the scientist said that earthquakes releases a lot of energy, and that's what starts the tsunami - that big amount of energy being released!" "Bingo!", said Mr. S. Let's take a look at this in another way. I will need a couple of volunteers.
"Derek and Jack, take the end of this", Mr. S. instructed as he held up a long spring. "Class, see if you can help them out. How many ways can they make a wave with this spring?" "They can go up or down, or sideways." The boys quickly demonstrated both types of waves. Have you seen these types of waves before?, queried their teacher. Katie said, "At the lake! The up and down ones are like when regular waves roll into shore. "Nice, Katie! Have we shown all the waves that we can?" "Wait!", blurted Jack. "I think I have another way." Jack cupped his hand over the end of the spring, then gave it a gentle slap. A wave pulsed down the spring toward Derek and back. "Good job!, said Mr. S. "Now, let's think about what we have here for a minute. What ingredients do we need for a wave?" "We need to have some kind of energy", said Blake. "Right, energy is a pretty important idea to hang on to. Anything else?" "Well, started Renee, you have to have something for the wave to move through - like a spring or water." "Yes!", said Mr. S. approvingly. In science, we call that a medium - that "something" that the wave moves through.There are some other things we need to learn in order to understand how waves operate in things like earthquakes and tsunamis. We are going to use a computer simulation for this next piece. Gather your group around a computer and let's shake things up a bit - virtually, that is!"
Resources
Instructional suggestions
As is apparent by examining the resources attached to this standard, wave content is typically covered in association with discussions of earthquakes and plate tectonics. It doesn't have to be, but if you are going to have a conversation with your students about earthquakes, then they need to understand the basics of wave properties, motion and energy transfer. Waves are a common phenomena. Everyone has some sort of experience with waves from fishing on a lake to body surfing on an ocean beach during a family vacation. Students have also all seen tsunami footage of either the 2004 Sumatra event or the 2011 Tohoku event. Because of this it is helpful to find out what students know or think they know about waves before you delve too deep into content. Eliciting their questions about waves at the onset would also be helpful in deciding the direction of your instruction.
A very common demonstration teachers typically use at the onset of an earthquake unit is to pull out their giant spring and start shaking it in front of the class to demonstrate waves. Think through what needs to be gained from seeing this demonstration. What questions could you pose to students to deepen their observations of either wave properties or wave behavior? Questions like the following may help you to get more out of this visual demonstration.
- How many different ways can I make a wave on this spring?
- How do the waves you see on this spring compare with the waves you all have seen in water?
- Do larger waves travel faster or slower than smaller waves?
- What role does the spring play here?
- What are three things about waves you think are important to remember about this demonstration?
- What questions about waves does this demonstration create?
Because seismic waves are difficult to observe directly or even in the lab, it is important that some sort of visualization piece be added to your instruction. There are a couple of links to websites that can provide your students with animations of seismic wave propagation. If they work with this on individual computers or in small groups, it would be beneficial to bring the entire class together, project the animation on a large screen and have a class discussion of what is taking place. Properties of the different types of seismic waves could be recorded on a simple chart in notebooks based on what students see and hear during your discussion.
The two tsunami generating events of the 21st century are significant opportunities for your students to understand the significance of earth science today. They need to be embedded and used in your instruction. making use of current events makes what you do and study in your classroom more relevant and relevance encourages engagement!
Selected activities
PhET contains a computer simulation activity Waves on a String that can provide students with an opportunity to discuss wave properties using common vocabulary and to predict the behavior of waves through varying medium. 8.2.3.1.1
Hippocampus is a project of the Monterey Institute for Technology and Education (MITE). The goal of HippoCampus is to provide high-quality, multimedia content on general education subjects to high school and college students free of charge. Wave Basics is a content rich site that allows students to receive content through a digitally interactive format. 8.2.3.1.1
NOVA recently aired a program called Deadliest Earthquakes that talked about the cutting edge of research into seismic waves. This show can be streamed online and would be a good enrichment of content for this standard. Supporting materials include an interview with a seismologist Frank Vernon which is quite enlightening. It is significant that about a month after this program aired, the earthquake/tsunami event happened in Japan. 8.2.3.1.1, 8.3.4.1.2
Tsunami Misconceptions: In this activity, students graph wave heights of various waves events on the Alaska coastline. From their data, they attempt to determine which incidents are tsunami events. This activity challenges the idea that tsunamis are based on wave height alone. 8.2.3.1.1, 8.3.1.1.3
Additional resources or links:
Earthquake Topics: Seismic Waves: From the USGS Earthquake Hazards Program, this site contains a comprehensive set of links related to seismic waves and earthquakes.
Understanding Waves gives explanation of waves in general and characteristics of waves; wavelength, amplitude, and frequency. The "wave generator" on the site allows students to manipulate these factors to see how this alters the size and motion of the wave.
How Tsunamis Work is an excellent account from the How Stuff Works site on how tsunamis are generated and how they differ from wind-induced waves.
Nova: Japan's Killer Quake: This eyewitness video account of the March 11, 2011 earthquake in Japan also covers the subsequent tsunami and nuclear crisis.
Incorporated Research Institutions for Seismology (IRIS) contains a wealth of resources designed to assist middle school geoscience teachers develop content knowledge of seismic events. This page provides short-segment video lectures to give rudimentary background information on the Earth and plate tectonics to teach how earthquakes happen and how they are studied. The video lecture series was intended for middle-school Earth-science teachers.
Airzooka: This amazing device launches a powerful vortex of air up to 20 feet. Powerful enough to blow out a candle from across the room! Safe for classroom use because it launches no projectile, only a strong puff of air. Can be used to talk about compression waves. Easy to use and requires no batteries. Colors may vary. This device may be ordered from Educational Innovations.
Vocabulary/Glossary: These definitions were taken from a pictorial digital dictionary operated by the USGS on this webpage.
- P wave: A P wave, or compressional wave, is a seismic body wave that shakes the ground back and forth in the same direction and the opposite direction as the direction the wave is moving.
- S wave: An S wave, or shear wave, is a seismic body wave that shakes the ground back and forth perpendicular to the direction the wave is moving.
- Surface wave: A surface wave is a seismic seismic wave that is trapped near the surface of the earth.
- Wavelength: The wavelength is the distance between successive points of equal amplitude and phase on a wave (for example, crest to crest or trough to trough).
- Frequency: The frequency is the number of times something happens in a certain period of time, such as the ground shaking up and down or back and forth during an earthquake.
- Amplitude: The amplitude is the size of the wiggles on an earthquake recording.
- Period: The period is the time interval required for one full cycle of a wave.
- Seismic wave: A seismic wave is an elastic wave generated by an impulse such as an earthquake or an explosion. Seismic waves may travel either along or near the earth's surface (Rayleigh and Love waves) or through the earth's interior (P and S waves).
- Seismogram: written recording of the earth's vibrations, produced by a seismograph.
- Epicenter: The epicenter is the point on the earth's surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture begins.
- Medium: Matter that the wave travels through. It may be solid, liquid or gas.
- Tsunami: A tsunami is a sea wave of local or distant origin that results from large-scale seafloor displacements associated with large earthquakes, major submarine slides, or exploding volcanic islands.
- Tidal wave: is a large movement of water formed by the funnelling of the incoming tide into a river or narrow bay.
Explore Learning: Gizmos Gizmos offers many computer simulations that are useful for students initially investigating a hard-to-visualize concept or in situations where an actual lab would be difficult to perform. Many of the Gizmos allow students to manipulate variables to see how that affect the outcome of the investigation. Two simulations relate directly to seismic waves. In "Recording Station", students learn how to determine the distance between the station and an earthquake based on the time difference between the arrival of the primary and secondary seismic waves. Students use multiple earthquake recording stations in "Determination of Epicenter" in order to determine the epicenter of an earthquake by analyzing the arrival of the primary and secondary seismic waves at each recording station. Gizmos is a subscription site, but free 30 day trial memberships are available.
Seismic Waves gives an explanation of seismic waves and how they move through the Earth. The "Wave Maker" simulation let's students visualize how P and S waves appear in motion. Students can check their understanding with a series of questions based on the simulation and explanations provided on the site.
Seismic wave visualization animations will allow students to picture the different types of waves and their motion behavior. The geology department at Michigan Technological University operates a seismic wave animation here and Incorporated Research Institutions for Seismology (IRIS) provides another means of visualizing the movement of seismic waves here.
The obvious cross-curricular connection here is with music. When talking about waves, using sound as an analogous example provides opportunities for talking about vibrations and how playing different musical instruments creates vibrations that our ears receive as sound waves. The vignette used for this standard illustrates how a teacher might use sound waves to help students make connections to waves applications in earth science.
Another connection could connect with geography, both physical and economic when seismic wave events are studied on the earth. Why does one country suffer a massive human disaster while a similar event elsewhere causes only minimal mayhem.
Assessment
Students: Include questions designed to probe student understanding of concepts, both formative and summative. Identify taxonomic level of questions.
Keeley, P. (2005). Uncovering student ideas in science, volume 1. Arlington, VA: NSTA Press.
The assessment probe "Making Sound" (p. 43) at first glance may appear to be unrelated to the benchmark here. However, to understand waves, the student needs to have a grasp of the idea of energy transfer from one medium to another (or across the same medium). Students are almost universally familiar with musical instruments. This probe nicely teases out the understanding (or lack thereof) that instruments need to vibrate in order to produce sound. Tying the knowledge gained from this probe to subsequent instructional strategies with common wave experiences, helps students eventually make the cognitive connection of the need for an energy transfer.
A written assessment for waves might include tasks such as:
Explain the "ingredients" needed to make a wave.
Draw an example of a wave and explain how it would form.
Draw and explain the various types of seismic waves.
Explain how scientists use seismic waves to learn more about an earthquake that has taken place.
A further and appropriate extension of this standard may be to have students research technologies used to find out more about seismic waves and what they tell us about a region's potential for deadly earthquakes. They might also research how scientists are conducting research to answer the big questions in seismology; How can you predict when and where an earthquake will happen and how strong will it be? This could serve as an additional performance assessment piece at the end of instruction.
Teachers:
How can the concepts relating to waves and transfer of energy be threaded seamlessly throughout the eighth grade science curriculum?
What are the essential questions students need to answer to demonstrate an understanding of this standard?
What content or process questions do I have about this standard and where can I go to get help?
Administrators:
If you walked in at the right time, you might see a very long spring stretched out in the front of the class with the teacher interacting with their class over the different student observations being made as the spring is vibrated. You might also experience a cacophony of "noise" coming from the room as students inquire into the ways that different instruments produce sound. If student notebooks were open, you would see the essential question for the day's lesson evident and if asked, students could tell you how they were trying to answer the question. You might also find the class happily interacting with content in an online environment rather than with textbooks.
Differentiation
Snow, D. (2003). Noteworthy perspectives: Classroom strategies for helping at-risk students (rev. ed.). Aurora, CO: Mid-continent Research for Education and Learning.
In 2002, McREL conducted a synthesis of recent research on instructional strategies to assist students who are low achieving or at risk of failure. From this synthesis of research, McREL identified six general classroom strategies that research indicates are particularly effective in helping struggling students achieve success:
Whole-class instruction that balances constructivist and behaviorist strategies
Cognitively oriented instruction which combines cognitive and meta-cognitive strategies with other learning activities
Small groups of either like-ability or mixed-ability students
Tutoring that emphasizes diagnostic and prescriptive interactions
Peer tutoring, including classroom-wide peer tutoring, peer-assisted learning strategies, and reciprocal peer tutoring
Computer-assisted instruction in which teachers have a significant role in facilitating activities
Complete results of this study may be downloaded here.
Herr, N. (2007). The sourcebook for teaching science.
This page contains strategies to help teachers better attend to the needs of their ELL learners. These strategies are grouped according to the following learning tasks: listening, visualization, interpersonal communication, laboratory, demonstrations, reading and writing, instruction and vocabulary.
Klentschy, M. (2010). Using science notebooks in middle school. Arlington, VA: NSTA Press.
Strategies:
Front-loading: Teachers plan for words that ELL students will encounter as they do inquiry and within the particular content being studied. They need to provide not only experience with vocabulary words (the "bricks"), but also the form and context in which they are used in spoken or written language ( the "mortar").
Word Wall: The teacher writes and discusses the needed vocabulary and posts the words on chart paper, sentence strips, or the board, making sure they remain in clear view for students to use as a resource when writing or speaking.
Kit Inventory: Uses science materials from the current lesson, allowing students to question and discuss the scientific name of these items, their use, and description of the properties of those materials (made of plastic, cylinder-shaped, etc.) in their investigations.
Everyday Words and Science Words: Purposely contrast the meaning of everyday words and science words (For example: "write down" versus "record"). These could be recorded on a chart for student reference.
Sentence Stems: Use abbreviated stems or scaffolds to help students begin writing in their science notebooks about their inquiry investigations:
- I observed _____.
- I wondered _____.
- I thought _____ would happen.
- Today I learned _____.
- Questions I have now _____.
Charts: Teachers should model a variety of charts and how to use them for recording and reading information. This helps students to have examples for eventually making their own charts, as well as to successfully use the vocabulary as it is presented in context.
Diagrams and Illustrations: Labeling diagrams, particularly those that the students drew themselves, reinforces the use of vocabulary and allows students to make relational connections to content.
Classification: Classification (which could include sorting, use of Venn Diagrams, T-charts, etc.) allows students to develop their understanding of the similarities and differences of (in this case) substances and to further interact with content specific words within the course context.
CLOZE: This strategy involves providing students with a reading passage in which content specific vocabulary (the "brick" words) have been left out. Words to include could be selected from a word wall or chart.
Concept Maps: Rather than merely learning recognition and definitions of science vocabulary, developing a concept map over the course of a unit helps students to tie those words into networks of related concepts. Maps can be added to as the unit and the understanding develop, possibly adding new ideas or connections in a different color.
G/T:
Teachers First is a educational support website that contains a list of strategies for working with gifted and talented students in your classroom. Many times it is not your "A" student that qualifies as Gifted and talented, but rather the student who is not achieving and being disruptive.
Cogito is a website set up as an online community for gifted and talented students. There is a link to their chemical sciences page that provides information designed it to capture and highlight all the interesting conversations, articles, experts, and activities going on around the chemical sciences on Cogito.
Students With Disabilities is a position statement by the National Science Teachers Association concerning the inclusion of and basic adaptations for students with disabilities in the science classroom.
Many of the adaptations listed below for ELL students also work well for special education students.
Technologies for Special Needs Students: In their newsletter, "Tech Trek", from the National Science Teachers Association, suggestions are given for using various technologies to make science more accessible to students. Included are ideas for computer-assisted instruction, assistive technologies (such as voice-recognition software), as well as internet links and additional resources.
Parents/Admin
All resources you use in class need to be accessible by parents and students from home, assuming they have a viable connection to the Internet. Using a district sponsored website like Moodle or Schoolwires provides access for families to relevant and current information for your course. Try to incorporate one question to homework assignments that requires parental input. If you are asking for opinions of something related to content, or some type of survey response to a question posed at the end of class, you will be generating opportunities for your students to talk about the content and ideas being discussed in class with family members. That qualifies as a positive course engagement outside of class and there can never be too many of them!
Sometimes you get lucky and find a parent of one of your students who works in a field that connects with the content of your course. If there are times when a question gets posed that you need help to answer, ask your class if any parents work in a related field and if the student could ask them the question that night. During an inquiry a class was doing about sidewalks, some concrete questions were posed that a student's parent, who worked as a mason, ended up answering for the class.