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6-8 > Earth Science
Grade level: 6-8 Subject: Earth Science Duration: Two class periods
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Students will understand the following:
1. There are three types of volcanoes: shield volcanoes, cinder cones, and composite volcanoes.
2. A shield volcano produces lava, or molten rock, when it erupts; a cinder cone produces ash; and a composite volcano is a combination of the first two.
3. Each type of volcano has a distinct shape.

To prepare for this activity, line a metal tray with wax paper and place it in the refrigerator until chilled.
Research materials about volcanoes (An article on volcanoes from a good encyclopedia will suffice.)
Computer with Internet access
Paraffin or broken crayons
Stove or hot plate
Double boiler
Wax paper
Metal tray
Large paper cup

1. Review with your students what they already know about volcanoes. Make sure they understand the termsmagma, lava, vent, and crater.Then tell them that there are three different types of volcanoes, and they are going to make models of each type.
2. On the chalkboard, write the names of the three different types of volcanoes: shield volcano, cinder cone, and composite volcano.
3. Have students use the research materials you have provided or the Internet to find a description for each type of volcano, an explanation of how each type is formed, and an actual example of each type. Before students begin making their models, they should know the following:
  1. A shield volcano is formed when a large amount of free-flowing lava, or molten rock, spills from avent, or opening in the earth, and spreads widely. The lava gradually builds up a low, broad, dome-shaped mountain. (Example: Mauna Loa in Hawaii.)
  2. A cinder cone builds up when mostly ash erupts from a vent and falls to the earth around the vent. The accumulated ash forms a cone-shaped mountain that appears flat on top. (Example: Paricutín in Mexico.)
  3. A composite volcano is formed when both lava and ash erupt from a vent. The materials pile up in alternate layers around the vent and form a cone-shaped mountain that comes to a point on top. (Examples: Mount Fuji in Japan, Mount Vesuvius in Italy.)
4. Divide your class into three groups, and assign each group one type of volcano to model.
5. To make a model of a shield volcano, students will need adult supervision. Have students follow these steps with the help of an adult:
  1. Melt 2 or more cups of paraffin or broken crayons in a double boiler, and very slowly pour the hot liquid onto a chilled metal tray covered with wax paper.
  2. Stop pouring when the pool of melted paraffin is 5 inches in diameter.
  3. Allow it to cool.
  4. Remelt the remaining paraffin, and then pour again.
  5. Stop and wait.
  6. Repeat several more times.
6. To make a model of a cinder cone, have students follow these steps:
  1. Pour sand from a large paper cup onto some newspaper.
  2. Continue pouring until your “volcano” is about 8 inches high.
7. To make a model of a composite volcano, have students follow the steps for the shield volcano, alternating layers of sand with the layers of melted paraffin or crayons.
8. Have students compare the models.
9. Each student should write a paragraph explaining how his or her model was constructed and which natural materials are represented by the materials used in the model.
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After researching the types of volcanoes, have students devise their own plans for making a model of each. They may choose whether or not to actually construct the models.
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Discussion Questions

1. How could you use the theory of plate tectonics to explain how a typical volcano works?
2. Explain how heat built up when Earth first formed. Speculate on how it might be sustained.
3. Hawaiian volcanoes produce two types of the same variety of lava. Pahoehoe is smooth and ropy; aa is chunky. Formulate a hypothesis as to why the same lava can have two different appearances.
4. Explain how gas concentrations could possibly signal a volcanic eruption.
5. Compare Kilauea to White Island volcano.
6. Describe the danger in an eruption such as the ones at Mt. Pinatubo and Mt. St. Helens.
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You can evaluate your students on their paragraphs using the following three-point rubric:
Three points:clear explanation of how model was constructed; accurate account of which natural materials the materials in the model represent; error-free writing
Two points:adequate explanation of how model was constructed; accurate account of which natural materials the materials in the model represent; some writing errors
One point:vague, sketchy explanation of how model was constructed; partially inaccurate account of which natural materials the materials in the model represent; numerous writing errors
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Think Thick
Volcanoes produce several materials—most notably lava. But not all lava is the same. Some lavas are thick, and some are thin, depending on when they cool or when additional minerals are added. The thickness (or thinness) of a substance, and the speed with which it moves, is called itsviscosity. Have students work with partners to measure viscosity with a simple tool they construct themselves. Instruct students to cut a round hole about the size of a small-diameter straw in the bottom of a Styrofoam drinking cup. Tell them to fill another cup with a measured amount of water, and then pour the water through the cup with the hole. Students should time the flow from beginning to end. Have students repeat with the same amount of thicker liquids, such as syrup, honey, or liquid glue. Then they can devise a measuring system for viscosity. Encourage students to compare their systems and decide which is best.

Pass the Plate, Please
Have students research plate tectonics and devise models to demonstrate how a typical volcano works, according to plate tectonics theory.

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Suggested Readings

Fire on the Mountain: The Nature of Volcanoes
Carl Johnson and Dorian Weisel, Chronicle Books, 1994
This book is a spectacular compilation of more than 100 color photographs of volcanoes and their aftereffects. Unlike many other treatises on volcanoes, the text of this work emphasizes the positive, rather than the devastating, ecological effects of volcanoes. Accompanied by color maps and a glossary to delight and inform younger and older students.

Quakes, Eruptions, and Other Geologic Cataclysms
Jon Erickson, Facts on File, 1994
The chapter entitled "Volcanic Eruptions" gives a history and descriptions of the world's most destructive volcanoes dating from 1600 B.C. through 1985 A.D. The relationship of volcanoes to other geological phenomena, such as extinctions, glaciers, landslides, and mudflows, are covered throughout the work. A glossary of geologic terms appropriate for middle and secondary school students is included.

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Volcano World
Volcano info for kids. Current nformation and a quiz. Slightly commercial but sponsored by NASA and NDAK.

Cascades Volcano Observatory
Volcanoes in the news. Disaster preparedness.

Virtual Volcano Tour
Student-created tour of Hawaiian volcano(es). Can also be accessed through the EBS Home Page.

Michigan Technological University Volcanoes Page
Information about current global volcanic activity, research in remote sensing of volcanoes and their eruptive products, hazard mitigation, links to government agencies and research institutions, and even some volcano humor.

The SRL Volcano Exhibit
Radar images of various volcanoes taken from space. GIF format pictures and accompanying text good for reports and presentations.

EBS VOLCANO! page with links to other sites.

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

speaker    plate tectonics
Definition:A theory of global dynamics having to do with the movement of a small number of semirigid sections of Earth’s crust, with seismic activity and volcanism occurring at the margins of these sections.
Context:Plate tectonics theory says Earth’s surface is a jigsaw of plates that drift fast and slow and in all directions, floating on a hot layer of rocks.

speaker    subduction
Definition:A geologic process in which one edge of one crustal plate is forced below the edge of another.
Context:Subduction occurs when one plate moves under another.

speaker    tephra
Definition:Post-eruption layers of land composed of volcanic lava and fragmented rock.
Context:They [volcanologists] map the build-up of land formed by lava and fragmented rock called tephra.

speaker    fumarole
Definition:A hole in a volcanic area from which hot smoke and gases escape.
Context:Trapped water in volcanoes is turned into steam. Jets of it spew through holes called fumaroles.

speaker    ground deformation
Definition:Bulges in the Earth’s surface caused by swelling in a volcano’s magma chamber.
Context:Bulges in the Earth’s surface are outward signs of swelling in the magma chamber. The movement is called ground deformation and is measured by surveying the landscape’s tilt.

speaker    pyroclastic flow
Definition:Eruption from a volcano consisting primarily of fragmented rock.
Context:The blast wave traveled downslope at the speed of sound, flattening whole forests and blasting 600 tons of ash into the atmosphere. Pyroclastic flow, the scientists called it.

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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:Earth science
Understands basic Earth processes.
Knows that the surface of the Earth changes; some changes are due to slow processes (e.g., erosion, weathering), and some changes are due to rapid processes (e.g., landslides, volcanoes, earthquakes).

Grade level:6-8
Subject area:Earth science
Understands basic Earth processes.
Knows that rock contains evidence of the minerals, temperatures and forces that created it.

Grade level:6-8
Subject area:Earth science
Understands basic Earth processes.
Knows how land forms are created through a combination of constructive and destructive forces: constructive forces include crustal deformation, volcanoes and deposition of sediment; destructive forces include weathering and erosion.

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