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6-8 > Weather
Grade level: 6-8 Subject: Weather Duration: Two class periods
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Objectives | Materials | Procedures | Adaptations | Discussion Questions | Evaluation | Extensions | Suggested Readings | Links | Vocabulary | Academic Standards | Credit
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Objectives
 



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Raging Planet: Avalanche




Students will understand the following:
1. Friction between snow or rocks and the underlying ground holds the snow or rocks in place on a slope, preventing avalanches and landslides.
2. In order for an avalanche or landslide to occur, friction must be overcome.
3. Substances that overcome friction, causing avalanches and landslides, are calledlubricants;they include water, ice, and sand.
4. Lubricants make the underlying surface slippery and provide a cushion for snow or rocks to move over.
5. The flatter or rounder the dry lubricant, the more slippery it makes the underlying surface.
Materials

Provide the following materials for each group:
Old textbook
Plastic bag
Half-meter piece of wood about 30 centimeters wide
Meterstick
Newspaper
Tape
Talcum powder
Sand
Pebbles
Marbles
Procedures

1. Ask your students if they can define the termsavalancheandlandslide. Make sure they understand that in an avalanche deep snow that has been lying on a slope breaks free from the underlying surface and crashes down the slope; a landslide is a similar phenomenon, involving rocks instead of snow. Students should know that both are potentially destructive and dangerous.
2. Ask students to think about the possible causes of an avalanche or landslide. Start them off by asking them to imagine a steep mountainside covered with snow. For weeks, the snow remains on the mountainside without moving. Then, one day, an avalanche occurs. Something must have changed, since things that are stationary do not begin to move for no reason at all. What changes could have caused the avalanche?
3. Tell your students that they are going to perform an experiment that might help them answer the question or confirm the answers that they have formulated. Then divide the class into groups to carry out the experiment.
4. Distribute materials to each group.
5. Have students fold up the newspaper and tape it to the floor to catch any debris.
6. Instruct students to place the piece of wood flat on the floor on top of the paper, and then stand the meterstick with the 0 end down at one end of the board.
7. Next, students should place the book on the board near the meterstick.
8. One student can then slowly lift the end of the board, causing the board to slope, until the book begins to slip.
9. Another student in the group should record the height of the board at the moment the book began slipping down the slope.
10. Have students repeat the experiment after putting talcum powder, then sand, then pebbles, then marbles beneath the book, each time recording the height of the board when the book begins to slip.
11. Discuss with the class the results of the experiment. Can students explain why the book began to slip with the end of the board at a lower level when talcum or other substances were added?
12. Explain that friction between the board and the book held the book in place. The added substances acted aslubricants,reducing the friction.
13. Have each student write a paragraph speculating as to what each lubricant used in the experiment may represent in nature. What if the lubricant were water or ice? How would water accumulate under a thick layer of snow on a mountain? They should conclude their paragraphs by telling what they think could have caused the avalanche they imagined before performing the experiment.
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Adaptations

Adaptations for Older Students:
Have students research the causes of avalanches and how avalanches can be predicted.
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Discussion Questions

1. Create a convincing argument for building at least one type of avalanche safeguard for your town. Assume the simplest plan will cost the town one million dollars and there is no money set aside for a project of this magnitude.
2. Develop a plan for how the town will fund construction of the safeguard and share it with the group.
3. Decide who will pay for safeguards around homes outside the central district.
4. After careful discussion, formulate a master plan that seems fair and benefits the majority of the residents.
5. Compare the three types of snow avalanches.
6. Brainstorm and share possible ways people could protect themselves from rock avalanches and pyroclastic flows.
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Evaluation

You can evaluate your students on their reports using the following three-point rubric:
  • Three points:reasoning carefully thought out; paragraph well organized and error-free

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  • Two points:adequate reasoning; paragraph lacking in organization with some errors

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  • One point:careless reasoning; paragraph lacking in organization with numerous errors

You can ask your students to contribute to the assessment rubric by determining criteria for persuasive reasoning.
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Extensions

Ski Our Mountain, Safest Around
Have students imagine that they manage a ski resort where avalanche barriers around chalets have recently been constructed. Their assignment is to create an illustrated brochure emphasizing safety to lure potential skiers to the resort.

Make a Break
Have your students make their own landslide/avalanche barriers. They will need a piece of wood or thick cardboard to represent a slope, thin pieces of wood for designing barriers, and a pair of dice or game pieces to represent buildings. They can use sand to represent snow or rocks. Instruct students to research avalanche barriers on the Internet and then design barriers of their own. They should place the dice about halfway down the slope without taping or gluing them; then tape or glue different types of barriers on the uphill side of the dice. Have students pour sand down the slope and observe the effects of the barriers, reinforcing them as necessary. Students should evaluate their designs, identifying those that work best, and then compare them with others to choose the best overall design.

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Suggested Readings

Snow Avalanche Hazards and Mitigation in the United States [online book]
National Research Council Commission on Engineering and Technical Systems, 1996
The publisher, the National Academy Press of the National Academy of Sciences, offers full online text with excellent digital imagery of avalanche phenomena.
http://www.nap.edu/readingroom/records/0309043352.html

The Avalanche Handbook
David McClung and Peter Schaerer, Mountaineers, 1993
The intended use of this handbook is a safety manual for hikers and other visitors/dwellers in mountainous regions. From it, much can be learned about the characteristics and behavior of avalanches, in addition to appropriate safety precautions.

“Avalanche!”
Patty Sullivan, Alaska, March 1997
Tom Abell has been buried by avalanches twice. The first time he survived by luck, the second time he was prepared with a homing device.

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Links

Outdoor Action Guide to Winter Camping
Winter camping and hiking basics and precautions. Avalanche safety.

Avalanche Education in the Schools
Somewhat commercial, but a good site! Trying to think of something besides a term paper? Here are some things we have assisted students with.

Avalanche Dogs!
Selecting and training avalanche dogs.

Avalanche Beware!
Facts on avalanches including: recognizing terrain, safety, human factors and rescues.

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Vocabulary

Click on any of the vocabulary words below to hear them pronounced and used in a sentence.

speaker    powder avalanche
Definition:A mass of loosely packed snow that begins with a piece of falling rock or ice.
Context:The largest and most destructive is a powder avalanche. A piece of falling ice or rock starts a mass of loose snow sliding down the mountain.

speaker    wet avalanche
Definition:A flow of snow, ice, rock, and other material that occurs as a result of thawing.
Context:The second type is a wet avalanche. These occur mostly late in the snow season when the snowpack is deep and the thaw is just beginning.

speaker    slab avalanche
Definition:A mass of snow, ice and possibly other material caused when a large slab of snow breaks free from the layers beneath.
Context:A slab avalanche is most deadly. The weight of a skier is enough to break a slab away from the layers beneath.

speaker    cornice
Definition:An overhanging mass of snow, ice, or rock usually on a ridge.
Context:Wind can also blow snow into a huge, dense drift or cornice on the crest of a ridge.

speaker    pyroclastic flow
Definition:A flow of hot gases, soot, and lava formed by volcanic action.
Context:This gray cloud is one of the most lethal forms of avalanche in the world. It comes out of an erupting volcano. It’s called a pyroclastic flow.

speaker    rock avalanche
Definition:A mass of boulders, rocks, and other material that slides down an incline riding on a layer of smaller rocks.
Context:Rock avalanches are the strangest of nature’s forces. Giant boulders “float” on tons of solid rock.

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Standards

This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
 
Grade level:6-8
Subject area:science
Standard:
Understands basic Earth processes.
Benchmarks:
Knows how land forms are created through a combination of constructive and destructive forces (e.g., constructive forces such as crustal deformation, volcanic eruptions, and deposition of sediment; destructive forces such as weathering and erosion).

Grade level:6-8
Subject area:science
Standard:
Understands basic Earth processes.
Benchmarks:
Knows factors that can impact the Earth’s climate (e.g., changes in the composition of the atmosphere; changes in ocean temperature; geological shifts such as meteor impacts, the advance or retreat of glaciers, or a series of volcanic eruptions).

Grade level:6-8
Subject area:science
Standard:
Understands basic concepts about the structure and properties of matter.
Benchmarks:
Knows that atoms often combine to form a molecule (or crystal), the smallest particle of a substance that retains its properties.

Grade level:6-8
Subject area:science
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Establishes relationships based on evidence and logical argument (e.g., provides causes for effects).

Grade level:6-8
Subject area:science
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows that scientific inquiry includes evaluating results of scientific investigations, experiments, observations, theoretical and mathematical models, and explanations proposed by other scientists (e.g., reviewing experimental procedures, examining evidence, identifying faulty reasoning, identifying statements that go beyond the evidence, suggesting alternative explanations).

Grade level:6-8
Subject area:science
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Knows possible outcomes of scientific investigations (e.g., some may result in new ideas and phenomena for study; some may generate new methods or procedures for an investigation; some may result in the development of new technologies to improve the collection of data; some may lead to new investigations).

Grade level:9-12
Subject area:science
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Understands the use of hypotheses in science (e.g., selecting and narrowing the focus of data, determining additional data to be gathered; guiding the interpretation of data).

Grade level:9-12
Subject area:science
Standard:
Understands the nature of scientific inquiry.
Benchmarks:
Designs and conducts scientific investigations by formulating testable hypotheses; identifying and clarifying the method, controls, and variables; organizing and displaying data; revising methods and explanations; presenting the results; and receiving critical response from others.

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Credit

Frank Weisel, science teacher, Tilden Middle School, Rockville, Maryland.
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