(5-8) F4

Science Curriculum Preview Committee Clarification of Learning Results

Revised 04/07/04

5-8

F4: Describe the factors that can cause short term and long term changes to the earth.

Organizing Questions

Classify these factors (specific) as affecting the earth in the short term or in the long term.

Describe some catastropic events that have effected the earth in the past or could affect the earth in the future.

Describe some slow processes that have shaped the earth over the long term, and what those effects have been.

Identify landforms and identify the processes that created them.

Describe the relation between mountain building and plate tectonics.

Describe the changes in Maine produced by glaciers and/or ice ages.

Elaboration
At this level, students are able to complete most of their understanding of the main features of the physical and biological factors that shape the face of the earth. This understanding will still be descriptive because the theory of plate tectonics will not be encountered formally until high school. Of course, students should see as great a variety of landforms and soils as possible. Benchmarks essay 4C

Specific Ideas

The earth processes we see today … are similar to those that have occurred in the past. Earth history is also influenced by occasional catastropes, such as the imnpact of an asteroid or comet. NSES p. 160 D21

Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destrcutive forces include weathering and erosion. NSES p. 160 D1c

The interior of the earth is hot. Heat flow and movement of material within the earth cause earthquakes and volcanic eruptions and create mountains and ocean basins. Gas and dust from large volcanoes can change the atmosphere. Benchmark 4C1

Some changes in the earth's surface are abrupt (such as earthquakes and volcanic eruptions) while other changes happen very slowly (such as uplift and wearing down of mountains). The earth's surface is shaped in part by the motion of water and wind over very long times, which act to level mountain ranges. Benchmark 4C2

Human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals released into the atmosphere, and intensive farming, have changed the earth's land, oceans, and atmosphere. Some of these changes have decreased the capacity of the environment to support some life forms. Benchmark 4C7

Climates have sometimes changed abruptly in the past as a result of changes in the earth's crust, such as volcanic eruptions or impacts of huge rocks from space. Even relatively small changes in atmospheric or ocean content can have widespread effects on climate if the change lasts long enough. Benchmark 4B6

Developmental & Instructional Implications
When change occurs in a variable, a major issue is the rate at which change occurs. Clearly students have to make sense of a constant rate of change before they can consider increasing or decreasing rates. Yet under-standing a constant rate of change is not as simple as it might seem, because of the difficulty of the idea of rate. Graphs would seem to be an immense help for semiquantitative descriptions of change--such as whether the rate is constant, increasing, saturating, etc. But the research results are that, unless the graph is of literal altitude, graph heights and slopes are puzzling to most children. The goal for all Americans should be modest: to understand a graph of any familiar variable against time in terms of reading it and interpreting its ups and downs in a story about what is going on. Eventually, steepness as well as direction of change can become part of the story. Benchmark 11C p. 271

Students should learn what causes earthquakes, volcanos, and floods and how those events shape the surface of the earth. Students, however, may show more interest in the phenomena than in the role the phenomena play in sculpting the earth. So teachers should start with students' immediate interests and work toward the science. Students may find it harder to take seriously the less-obvious, less-dramatic, long-term effects of erosion by wind and water, annual deposits of sediment, the creep of continents, and the rise of mountains. Students' recognition of those effects will depend on an improving sense of long time periods and familiarity with the effect of multiplying tiny fractions by very large numbers (in this case, slow rates by long times). Benchmark 4C essay p. 71

Examples

Back to Big Ideas Grid F Back to Standard F Back to Index

Organizing Questions	Classify these factors (specific) as affecting the earth in the short term or in the long term. Describe some catastropic events that have effected the earth in the past or could affect the earth in the future. Describe some slow processes that have shaped the earth over the long term, and what those effects have been. Identify landforms and identify the processes that created them. Describe the relation between mountain building and plate tectonics. Describe the changes in Maine produced by glaciers and/or ice ages.
Elaboration	At this level, students are able to complete most of their understanding of the main features of the physical and biological factors that shape the face of the earth. This understanding will still be descriptive because the theory of plate tectonics will not be encountered formally until high school. Of course, students should see as great a variety of landforms and soils as possible. Benchmarks essay 4C
Specific Ideas	The earth processes we see today … are similar to those that have occurred in the past. Earth history is also influenced by occasional catastropes, such as the imnpact of an asteroid or comet. NSES p. 160 D21 Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destrcutive forces include weathering and erosion. NSES p. 160 D1c The interior of the earth is hot. Heat flow and movement of material within the earth cause earthquakes and volcanic eruptions and create mountains and ocean basins. Gas and dust from large volcanoes can change the atmosphere. Benchmark 4C1 Some changes in the earth's surface are abrupt (such as earthquakes and volcanic eruptions) while other changes happen very slowly (such as uplift and wearing down of mountains). The earth's surface is shaped in part by the motion of water and wind over very long times, which act to level mountain ranges. Benchmark 4C2 Human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals released into the atmosphere, and intensive farming, have changed the earth's land, oceans, and atmosphere. Some of these changes have decreased the capacity of the environment to support some life forms. Benchmark 4C7 Climates have sometimes changed abruptly in the past as a result of changes in the earth's crust, such as volcanic eruptions or impacts of huge rocks from space. Even relatively small changes in atmospheric or ocean content can have widespread effects on climate if the change lasts long enough. Benchmark 4B6
Developmental & Instructional Implications	When change occurs in a variable, a major issue is the rate at which change occurs. Clearly students have to make sense of a constant rate of change before they can consider increasing or decreasing rates. Yet under-standing a constant rate of change is not as simple as it might seem, because of the difficulty of the idea of rate. Graphs would seem to be an immense help for semiquantitative descriptions of change--such as whether the rate is constant, increasing, saturating, etc. But the research results are that, unless the graph is of literal altitude, graph heights and slopes are puzzling to most children. The goal for all Americans should be modest: to understand a graph of any familiar variable against time in terms of reading it and interpreting its ups and downs in a story about what is going on. Eventually, steepness as well as direction of change can become part of the story. Benchmark 11C p. 271 Students should learn what causes earthquakes, volcanos, and floods and how those events shape the surface of the earth. Students, however, may show more interest in the phenomena than in the role the phenomena play in sculpting the earth. So teachers should start with students' immediate interests and work toward the science. Students may find it harder to take seriously the less-obvious, less-dramatic, long-term effects of erosion by wind and water, annual deposits of sediment, the creep of continents, and the rise of mountains. Students' recognition of those effects will depend on an improving sense of long time periods and familiarity with the effect of multiplying tiny fractions by very large numbers (in this case, slow rates by long times). Benchmark 4C essay p. 71
Examples