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6-8 > Earth Science | |
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| Grade level: 6-8 |
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Subject: Earth Science |
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Duration: Two class periods |
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Students will understand the following:
| 1. | As glaciers move, they create a variety of patterns on landforms by a process called glacial scraping. |
| 2. | The scraping patterns left by a glacier depend on how the glacier moved over the landform. |
| 3. | The evidence of glaciation left by glacial scraping provides clues to the climate in a particular place over a long period of time. |
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You will need access to a freezer. Photographs of glacial-scraping patterns would enhance the lesson. In addition, the following materials should be available for each group:
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Plastic cup |
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Angular gravel |
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Tap water |
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Plastic wrap |
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Tape |
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Paper plate |
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Smooth piece of wood |
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| 1. | Review with your students what they have learned about glaciers. They should be able to define glacier and explain why glaciers move over landforms. |
| 2. | Ask students how they think scientists can tell if glaciers have moved over the land in a particular area. Explain that rocks and gravel freeze into the ice and are dragged over the land by the bottom surface of a glacier. How would the land over which a glacier has moved be affected? What evidence of glaciation do glaciers leave behind? |
| 3. | Tell your students that they will participate in an activity that will simulate the way landforms are affected by glaciation. |
| 4. | Divide the class into groups, and have each group create its own miniature glacier as follows:
- Have students half-fill a paper cup with angular gravel.
- Cover the gravel with about an inch of water.
- Securely tape plastic wrap over the top of the cup.
- Flip the cup onto a paper plate.
- Leave the inverted cup in a freezer overnight.
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| 5. | When the “glaciers” are frozen solid, have students peel off the paper and scrape them, gravel end down, over a smooth piece of wood. To simulate the action of a glacier, students should scrape in only one direction, since glaciers move only one way. |
| 6. | Ask students to observe the patterns the gravel has made on the wood. How would they compare these to the patterns made on landforms by a real glacier? (If possible, provide photographs of actual glacial scraping.) |
| 7. | Have each student sketch their patterns and write a short paragraph explaining what they can infer about the way real glaciers affect the landforms over which they move. |
| 8. | Discuss with the class how patterns of glaciation provide clues to the climate in a particular area over time. For example, if evidence of glacial scraping is found in an area that is too warm for glaciers to exist, what can we infer about how the climate in that area has changed over a long period of time? |
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Adaptations for Older Students:
Have students research different kinds of glaciers and the ways in which they move.
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| 1. | Speculate why icebergs are so hard to destroy. List your reasons. |
| 2. | Water expands when it freezes. This is the underlying reason why an iceberg floats—it is less dense than water. So, why does the amount of underwater ice in an iceberg vary? |
| 3. | If you were a ship’s captain and had to sail into iceberg-infested waters, what precautions would you take? |
| 4. | Speculate whether icebergs could be used constructively as a resource for freshwater. |
| 5. | Discuss thermohaline circulation and its global effects. |
| 6. | Analyze the global effects of the current annual increase in icebergs. Relate the analysis to present-day processes. |
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You can evaluate your students on their sketches and paragraphs using the following three-point rubric:
Three points: sketches carefully and accurately drawn; paragraphs clear, complete, and error-free
Two points: sketches adequate; paragraphs sufficiently clear, but with some errors
One point: sketches adequate; paragraphs lacking in clarity with numerous errors
You can ask your students to contribute to the assessment rubric by determining what information the report should provide. |
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Tow Your Berg
Icebergs, huge masses of ice that have broken off glaciers and floated out to sea, are made of freshwater, not salt water. Therefore, it has been suggested that ships could tow icebergs to arid areas of the world, where the ice could be melted and the water used for drinking and irrigation. Have students use a world map to locate areas that would be prime candidates for “iceberg water.” They should draw water routes to the areas they select. As a class, discuss the limitations of such a program.
Sounds of Icebergs
Before the development of radar, sonar, and the Global Positioning System, sailors on watch in the Arctic region would listen for distinctive sounds to help them determine whether icebergs were close or far away. Encourage students to discover what an iceberg sounds like as it melts. Students can simulate the sounds by making a miniature iceberg out of soda water. Have them refrigerate an unopened 1-liter bottle of soda (seltzer) water overnight. Then have them put the bottle in the freezer for about half an hour until the liquid forms small ice crystals (but does not freeze completely). Students should pour the almost-frozen liquid into a small paper cup and freeze the cup and its contents. Once the “iceberg” is frozen, they should remove it from its cup, place it in a plastic container, half-fill the container with tepid tap water, and put a lid on the container. Tell students to listen closely to any sounds coming from the container. Then discuss the class findings. Was there a change in the sound over time? Have each student draw a series of three labeled sketches depicting how icebergs emit sounds as they melt. As a class, discuss how sailors might have used this information.
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“How Warming Helps Antarctic Ice”
Richard Monastersky. Science News, August 1997.
This brief article discusses the effect of global warming in Antarctica—causing the ice to thicken rather than thin.
“Iceberg, Dead Ahead”
Martin Miller. Los Angeles Times, April 15, 1998.
In the aftermath of the Titanic disaster, the International Ice Patrol was formed to patrol the North Atlantic in search of icebergs.
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Click on any of the vocabulary words below to hear them pronounced and used in a sentence.
Definition: Air bubbles released from melting icebergs.
Context: Bergie seltzer is released when icebergs melt as they drift along in Baffin Bay. The fizzing noise is produced because the air bubbles are under high pressure.
Definition: Separated or broken so that a part becomes detached.
Context: One million tons of ice are calved each day from a 300-foot glacial wall.
Definition: Mysterious or obscure.
Context: Icebergs are enigmatic. How they move, how thick-skinned they are, how much damage they can do are all subject to debate.
Definition: Frozen seawater.
Context: Sea ice forms when part of the sea freezes.
Definition: A circulation of seawater resulting from a combination of temperature and salinity effects.
Context: Thermohaline circulation is the conveyor belt that brings warm water to northern Europe.
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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 the Mid-continent Research for Education and Learning in Aurora, Colorado.
Grade level: 6-8, 9-12
Subject area: science
Standard:
Understands basic features of the Earth.
Benchmarks:
(6-8) 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). (6-8) Knows the processes involved in the water cycle (e.g., evaporation, condensation, precipitation, surface run-off, percolation) and their effects on climatic patterns. (6-8) Knows the properties that make water an essential component of the Earth system (e.g., its ability to act as a solvent, its ability to remain a liquid at most Earth temperatures). (6-8) Knows that the Sun is the principle energy source for phenomena on the Earth's surface (e.g., winds, ocean currents, the water cycle, plant growth). (9-12) Knows that weather and climate involve the transfer of energy in and out of the atmosphere.
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Frank Weisel, earth science teacher, Tilden Middle School, Rockville, Maryland. |
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