Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum

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Teaching Geography: Workshop 1


Introductory Material for Workshop 1

The following material comes from Chapters 2 and 3 of Geography for Life. You may read it here, in the print guide, or in Geography for Life. Supplemental materials are available in Resources.

The Components of Geography Education

Organization of Geography
Geography is composed of three interrelated and inseparable components: subject matter, skills, and perspectives. Subject matter is a distillation of essential knowledge and is the foundation for the geography standards. Subject matter is the basis on which geographic skills are brought to bear. These skills are: (1) asking geographic questions, (2) acquiring geographic information, (3) organizing geographic information, (4) analyzing geographic information, and (5) answering geographic questions. Knowledge and skills must be considered from two perspectives: spatial and ecological.

Mastering any single component of geography is not equivalent to mastering geography. All three—subject matter, skills, and perspectives—are necessary to being geographically informed. None can stand alone.

There is a related chain of knowledge that the geographically informed person must appreciate and command. Knowing population growth rates is not sufficient unless that knowledge can be related to an understanding of the resource base—the distribution of arable land, climate patterns—and to the transportation system that moves food supplies to consumers, and so on. Likewise, knowing where to find information on the distribution of population is not sufficient unless you know how to evaluate the reliability of that information, can relate it to maps of arable land and transportation routes, and can then speculate on the impact of changing population policies, migration patterns, or new crops on the patterns of people and rates of food production. This process returns you to the subject of population growth rates, completing a chain of knowledge involving people, places, and environments.

Space and Place
Understanding the relationships between people, places, and environments depends upon an understanding of space. Space is the environmental stage upon which the drama of geography is played out, and places are particular points on the environmental stage where the action occurs. In this respect, there is a parallel with the approach of history. History is concerned with understanding the temporal dimension of human experience (time and chronology). Geography is concerned with understanding the spatial dimension of human experience (space and place).

Space in the world is identified in terms of location, distance, direction, pattern, shape, and arrangement. Place is identified in terms of the relationships between physical environmental characteristics, such as climate, topography, and vegetation, and human characteristics such as economic activity, settlement, and land use. Together, these characteristics make each particular place meaningful and special to people. Place, in fact, is space endowed with physical and human meaning. It is the fascination with and exploration of space and place that give geography its way of understanding the world.

The Subject Matter
The roots of the word geography are found in two Greek words: geo, meaning Earth, and graphia, meaning description or depiction. The purpose of geography, therefore, is to describe or depict Earth. But there is no single way of doing that. Rather, Earth can be looked at in various ways.

As a physical object, it is an oblate spheroid with an equatorial circumference of approximately 24,902 miles; its surface is covered by water and land in a ratio of approximately 2.3:1; and that surface ranges from 29,028 feet above sea level to 35,840 feet below sea level (the top of Mount Everest to the bottom of the Mariana Trench).

As a physical environment, Earth is characterized by large-scale processes, such as the atmospheric jet streams that snake across its surface, and large-scale landforms, such as the Ring of Fire surrounding the Pacific Basin.

As a place in which humans can live, it offers such diverse habitats as the permafrost of Siberia, the tropical rain forest of the Congo River basin, and the Atacama Desert of Chile.

As a place in which humans do live, it displays intricate patterns of environmental modification (e.g., the polderlands of the Netherlands, or the terraced hills of the Philippines), as well as varied patterns of land use (e.g., the densely populated area of Hong Kong, the sparsely peopled central desert of Australia, and the automobile-based sprawl of southern California).

Geographers look at Earth in all of these ways: as a physical object, as a physical environment, and as a human place. Geographers also look at the world as a whole, to understand the connections between places and to recognize that the local affects the global and vice versa. But in order to study Earth as the home of people, geographers must develop a framework that cuts into the connections between places.

Our framework consists of two levels. At the first level, the subject matter of geography is divided into six essential elements. By essential we mean that each piece is central and necessary; we must look at the world in this way. By element we mean that each piece is a building block for the whole. At the second level, each essential element contains a number of geography standards, and each geography standard contains a set of related ideas and approaches to the subject matter of geography.

The Six Essential Elements
The first element, The World in Spatial Terms, captures the essence of the geographic eye: the structuring of geographic information, the ordering of knowledge into mental maps, and the spatial analysis of that information. Given this essential grounding in the geographic way of approaching the world, the second element, Places and Regions, applies that geographic eye to the world: places and regions are the basic units of geography, and those units are seen differently by different people. The third and fourth elements, Physical Systems and Human Systems, cover the specific content of geography. Physical Systems looks at physical processes (climate, landforms, etc.) and then organizes these processes into functional units: ecosystems. Human Systems begins with population and then considers human activities, from culture to economics, settlement, and conflict and cooperation. The fifth element, Environment and Society, reintegrates the content of geography by emphasizing the interaction between physical and human systems and identifying the central role of resources in environment-society links. The sixth element, The Uses of Geography, shows how geography, taken as a whole, enables us to understand the past, interpret the present, and plan for the future.

The Eighteen Standards
Physical and human phenomena are spatially distributed over Earth's surface. The outcome of Geography for Life is a geographically informed person who (1) sees meaning in the arrangement of things in space; (2) sees relations between people, places, and environments; (3) uses geographic skills; and (4) applies spatial and ecological perspectives to life situations.

The World in Spatial Terms
Geography studies the relationships between people, places, and environments by mapping information about them into a spatial context.

The geographically informed person knows and understands:
1. How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective
2. How to use mental maps to organize information about people, places, and environments in a spatial context
3. How to analyze the spatial organization of people, places, and environments on Earth's surface

Places and Regions
The identities and lives of individuals and peoples are rooted in particular places and in those human constructs called regions.

The geographically informed person knows and understands:
4. The physical and human characteristics of places
5. That people create regions to interpret Earth's complexity
6. How culture and experience influence people's perceptions of places and regions

Physical Systems
Physical processes shape Earth's surface and interact with plant and animal life to create, sustain, and modify ecosystems.

The geographically informed person knows and understands:
7. The physical processes that shape the patterns of Earth's surface
8. The characteristics and spatial distribution of ecosystems on Earth's surface

Human Systems
People are central to geography in that human activities help shape Earth's surface, human settlements and structures are part of Earth's surface, and humans compete for control of Earth's surface.

The geographically informed person knows and understands:
9. The characteristics, distribution, and migration of human populations on Earth's surface
10. The characteristics, distribution, and complexity of Earth's cultural mosaics
11. The patterns and networks of economic interdependence on Earth's surface
12. The processes, patterns, and functions of human settlement
13. How the forces of cooperation and conflict among people influence the division and control of Earth's surface

Environment and Society
The physical environment is modified by human activities, largely as a consequence of the ways in which human societies value and use Earth's natural resources, and human activities are also influenced by Earth's physical features and processes.

The geographically informed person knows and understands:
14. How human actions modify the physical environment
15. How physical systems affect human systems
16. The changes that occur in the meaning, use, distribution, and importance of resources

The Uses of Geography
Knowledge of geography enables people to develop an understanding of the relationships between people, places, and environments over time - that is, of Earth as it was, is, and might be.

The geographically informed person knows and understands:
17. How to apply geography to interpret the past
18. How to apply geography to interpret the present and plan for the future

Using the Eighteen Standards
While all of the National Geography Standards are applicable and relevant to all states and school districts, different emphases are possible and desirable. A state such as Alaska might emphasize the three Environment and Society standards, interpreting them prospectively by focusing on resources and the potential impacts of human activities on Alaska's physical environment. A state such as Pennsylvania might take the same three standards, interpreting them retrospectively by focusing on the environmental consequences of resource extraction and exhaustion in Pennsylvania. Similarly, an urban school in Detroit might implement National Geography Standard 10—the characteristics, distribution, and complexity of Earth's cultural mosaics—by emphasizing intraurban migration, neighborhood formation, and ethnic diversity; whereas a rural school in Montana might emphasize National Geography Standard 12—the processes, patterns, and functions of human settlement—and concentrate on the economic and social problems of low density, dispersed settlements.

Illustrative examples can be tailored to local contexts. In discussing migration in National Geography Standard 9, a school district in California might examine migration from Southeast Asia, a school district in Florida might devote attention to migration from the Caribbean, and a school district in Texas might consider migration from Mexico and Central America. Similarly, a New England school district might discuss migration of French Canadians in the nineteenth century whereas a school district in Louisiana might look at the migration of Acadians in the early eighteenth century. School districts in Chicago and Baltimore might look at the flows of African Americans from Mississippi and Alabama in the early and middle twentieth century; whereas schools in Cincinnati and Cleveland might choose migration from Appalachia during the same period. In all cases, despite differences in specific place and time, the basic geographic concepts would be identical: push and pull factors, migration streams, migration fields, distances, and the role of intervening opportunities.

Geographic Skills and Perspectives

Geographic Skills
Geographic skills provide the necessary tools and techniques for us to think geographically. They are central to geography's distinctive approach to understanding physical and human patterns and processes on Earth. We use geographic skills when we make decisions important to our well-being: where to buy or rent a home; where to get a job; how to get to work or to a friend's house; where to shop, vacation, or go to school. All of these decisions involve the ability to acquire, arrange, and use geographic information. Daily decisions and community activities are linked to thinking systematically about environmental and societal issues. Community decisions relating to problems of air, water, and land pollution or locational issues, such as where to place industries, schools, and residential areas, also require the skillful use of geographic information. Business and government decisions, from the best site for a supermarket or a regional airport to issues of resource use or international trade involve the analysis of geographic data.

Geographic skills help us to make reasoned political decisions. Whether the issues involve the evaluation of foreign affairs and international economic policy or local zoning and land use, the skills enable us to collect and analyze information, come to an informed conclusion, and make reasoned decisions on a course of action. Geographic skills also aid in the development and presentation of effective, persuasive arguments for and against matters of public policy.

The Rationale for Geographic Skills
The geographic skills that a geographically informed person should have consist of five sets adapted from the Guidelines for Geographic Education: Elementary and Secondary Schools, prepared by the Joint Committee on Geographic Education and published in 1984 by the Association of American Geographers and the National Council for Geographic Education:

  1. 1. Asking geographic questions
  2. 2. Acquiring geographic information
  3. 3. Organizing geographic information
  4. 4. Analyzing geographic information
  5. 5. Answering geographic questions

Following is a brief discussion of the principles underlying the five skills sets, followed by the presentation of skills.

1. Asking Geographic Questions
Successful geographic inquiry involves the ability and willingness to ask, speculate on, and answer questions about why things are where they are and how they got there. Students need to be able to pose questions about their surroundings: Where is something located? Why is it there? With what is it associated? What are the consequences of its location and associations? What is this place like?

Students should be asked to speculate about possible answers to questions because speculation leads to the development of hypotheses that link the asking and answering stages of the process. Hypotheses guide the search for information.

Geography is distinguished by the kinds of questions it asks: the "where" and "why there" of a problem. It is important that students develop and practice the skills of asking such questions for themselves. The task can be approached by giving students practice in distinguishing geographic from nongeographic questions and by presenting students with issues and asking them to develop geographic questions. At higher grade levels students can identify geographic problems and ways in which an application of geography can help solve problems or resolve issues.

2. Acquiring Geographic Information
Geographic information is information about locations, the physical and human characteristics of those locations, and the geographic activities and conditions of the people who live in those places. To answer geographic questions, students should start by gathering information from a variety of sources in a variety of ways. They should read and interpret all kinds of maps. They should compile and use primary and secondary information to prepare quantitative and qualitative descriptions. They should collect data from interviews, fieldwork, reference material, and library research.

The skills involved in acquiring geographic information include locating and collecting data, observing and systematically recording information, reading and interpreting maps and other graphic representations of spaces and places, interviewing, and using statistical methods.

Primary sources of information, especially the result of fieldwork performed by the students, are important in geographic inquiry. Fieldwork involves students conducting research in the community by distributing questionnaires, taking photographs, recording observations, interviewing citizens, and collecting samples. Fieldwork helps arouse the students' curiosity and makes the study of geography more enjoyable and relevant. It fosters active learning by enabling students to observe, ask questions, identify problems, and hone their perceptions of physical features and human activities. Fieldwork connects the students' school activities with the world in which they live.

Secondary sources of information include texts, maps, statistics, photographs, multimedia, computer databases, newspapers, telephone directories, and government publications.

Tertiary sources such as encyclopedias report information compiled from secondary sources and are important in some research situations.

3. Organizing Geographic Information
Once collected, the geographic information should be organized and displayed in ways that help analysis and interpretation. Data should be arranged systematically. Different types of data should be separated and classified in visual, graphic forms: photographs, aerial photos, graphs, cross sections, climagraphs, diagrams, tables, cartograms, and maps. Written information from documents or interviews should be organized into pertinent quotes or tabular form.

There are many ways to organize geographic information. Maps play a central role in geographic inquiry, but there are other ways to translate data into visual form, such as by using graphs of all kinds, tables, spreadsheets, and time lines. Such visuals are especially useful when accompanied by clear oral or written summaries. Creativity and skill are needed to arrange geographic information effectively. Decisions about design, color, graphics, scale, and clarity are important in developing the kinds of maps, graphs, and charts that best reflect the data.

Geography has been called "the art of the mappable." Making maps should be a common activity for all students. They should read (decode) maps to collect information and analyze geographic patterns and make (encode) maps to organize information. Making maps can mean using sketch maps to make a point in an essay or record field observations. It can mean using symbols to map data on the location of world resources or producing a county-level map of income in a state. It can even mean mapping the distribution of fire-ant mounds in a field or trash on a school playground. For students, making maps should become as common, natural, and easy as writing a paragraph. They should be skilled in interpreting and creating map symbols, finding locations on maps using a variety of reference systems, orienting maps and finding directions, using scales to determine distance, and thinking critically about information on maps.

4. Analyzing Geographic Information
Analyzing geographic information involves seeking patterns, relationships, and connections. As students analyze and interpret information, meaningful patterns or processes emerge. Students can then synthesize their observations into a coherent explanation. Students should note associations and similarities between areas, recognize patterns, and draw inferences from maps, graphs, diagrams, tables, and other sources. Using simple statistics, students can identify trends, relationships, and sequences.

Geographic analysis involves a variety of activities. It is sometimes difficult to separate the processes involved in organizing geographic information from the procedures used in analyzing it. The two processes go on simultaneously in many cases. But in other instances, analysis follows the manipulation of raw data into an easily understood and usable form. Students should scrutinize maps to discover and compare spatial patterns and relationships; study tables and graphs to determine trends and relationships between and among items; probe data through statistical methods to identify trends, sequences, correlations, and relationships; examine texts and documents to interpret, explain, and synthesize characteristics. Together these analytic processes lead to answers to the questions that first prompted an inquiry and to the development of geographic models and generalizations. These are the analytical skills that all students need to develop.

5. Answering Geographic Questions
Successful geographic inquiry culminates in the development of generalizations and conclusions based on the data collected, organized, and analyzed. Skills associated with answering geographic questions include the ability to make inferences based on information organized in graphic form (maps, tables, graphs) and in oral and written narratives. These skills involve the ability to distinguish generalizations that apply at the local level from those that apply at the global level (issues of scale are important in developing answers to geographic questions).

Generalizations are the culmination of the process of inquiry, and they help to codify understanding. Developing generalizations requires that students use the information they have collected, processed, and analyzed to make general statements about geography. At other times, however, students use the evidence they have acquired to make decisions, solve problems, or form judgments about a question, issue, or problem.

Geographic generalizations can be made using inductive reasoning or deductive reasoning. Inductive reasoning requires students to synthesize geographic information to answer questions and reach conclusions. Deductive reasoning requires students to identify relevant questions, collect and assess evidence, and decide whether the generalizations are appropriate by testing them against the real world. Students should have experience in both approaches to learning.

Students should also be able to communicate clearly and effectively, especially as they learn to answer geographic questions. It is a skill linked closely to good citizenship. Students can develop a sense of civic responsibility by disseminating the answers they have discovered in geographic inquiry. They can display geographic information in many engaging and effective ways—for example, by using multimedia, such as combinations of pictures, maps, graphs, and narratives, to present a story or illuminate a generalization. Geographic information can also be presented through the use of poems, collages, plays, journals, and essays. Every medium chosen to present geographic information to answer questions or address an issue or problem should stimulate inquiry and communicate clearly. Choosing the best means of presenting answers to geographic questions is an important skill.

Students should also understand that there are alternative ways to reach generalizations and conclusions. There are many types of knowledge, and many levels of reality and meaning. Teachers should encourage students to develop multiple points of view and to seek multiple outcomes to problems. This process should include collecting many kinds of data, including personal, subjective information, from a variety of sources.

The fifth skill set represents the last step in the process of geographic inquiry. But it is not really the end, because the process usually begins again with new questions suggested by the conclusions and generalizations that have been developed. These questions, often posed as hypotheses to be tested, provide a way to review generalizations. Each question answered, decision reached, or problem solved leads to new issues and new problems. Geographic learning is a continuous process that is both empowering and fascinating.

Developing Geographic Skills

It is essential that students develop the skills that will enable them to observe patterns, associations, and spatial order. Many of the skills that students are expected to learn involve the use of tools and technologies that are part of the process of geographic inquiry. Maps are essential tools of geography because they assist in the visualization of space.

Other tools and technologies, such as satellite-produced images, graphs, sketches, diagrams, and photographs, are also integral parts of geographic analysis. The rate of growth of an urban area, for example, can be observed by comparing old and new photographs. Large-scale land-use changes can be made clear by comparing images taken over a period of years.

A new and important tool in geographic analysis is the spatial database, or geographic information system (GIS). (See Geography for Life, Appendix E.) Geographic information systems make the process of presenting and analyzing geographic information easier, so they can accelerate geographic inquiry. Spatial databases can also be developed in the classroom using paper and pencil.

Many of the capabilities that students need to develop geographic skills are termed critical-thinking skills. Such skills are not unique to geography and involve a number of generic thinking processes, such as knowing, inferring, analyzing, judging, hypothesizing, generalizing, predicting, and decision-making. These have applications to all levels of geographic inquiry and constitute the bases on which students can build competencies in applying geographic skills to geographic inquiry.

Geographic skills develop over the entire course of the students' school years, and for each of the three successive grade levels discussed (K-4, 5-8, 9-12; see Geography for Life, pp. 46-56). Teachers and other curriculum developers will need to recognize that the students' mastery of geographic skills must be sequenced effectively so that the students retain and build on their understanding.

Geographic Perspectives

A perspective is one point of view among many competing ways of interpreting the meanings of experiences, events, places, persons, cultures, and physical environments. Having a perspective means looking at our world through a lens shaped by personal experience, selective information, and subjective evaluation. A perspective provides a frame of reference for asking and answering questions, identifying and solving problems, and evaluating the consequences of alternative actions. It is essential to be aware that many perspectives exist and that learning to understand the world from many points of view enhances our knowledge and skills. It is also essential to realize that our perspectives incorporate all life experiences and draw upon knowledge from many fields of inquiry. Therefore people cannot be neatly boxed into specific perspective types regardless of their cultural experiences, ethnic backgrounds, age, gender, or any other characteristic. Geographically informed people know how to contemplate, understand, and apply two specific geographic perspectives, along with complementary disciplinary and personal perspectives.

The two specific geographic perspectives are the spatial perspective and the ecological perspective. Geographic perspectives bring societies and nature under the lens of geography for interpretation and explanation. Geographic perspectives encompass understanding spatial patterns and processes on Earth and comprehending that Earth is composed of living and nonliving elements interacting in complex webs of relationships within nature and between nature and societies. A fully developed set of geographic perspectives, therefore, requires the use of both spatial and ecological points of view.

Knowledge is one fabric woven from many distinctive fields of learning and is organized by different intellectual frameworks. Although each field of study represents distinctive areas of inquiry, specialization, and perspectives, diverse sets of questions are needed to reveal the complexities of nature and societies. Consequently, although spatial and ecological perspectives are hallmarks of the geographic way of looking at the world, additional perspectives are required for us to become fully informed.

The Spatial Perspective

As history is concerned with the temporal dimension of human experience (time and chronology), geography is concerned with the spatial dimension of human experience (space and place). The space of Earth's surface is the fundamental characteristic underpinning geography. The essential issue of "whereness"—embodied in specific questions such as “Where is it?” and “Why is it there?”—helps humans to contemplate the context of spatial relationships in which the human story is played out.

Understanding spatial patterns and processes is essential to appreciating how people live on Earth. People who approach knowing and doing with a habit of inquiring about whereness possess a spatial perspective.

The Ecological Perspective

Earth is composed of living and nonliving elements interacting in complex webs of ecological relationships that occur at multiple levels. Humans are part of the interacting and interdependent relationships in ecosystems and are one among many species that constitute the living part of Earth. Human actions modify physical environments and the viability of ecosystems at local to global scales. The survival of humans and other species requires a viable global ecosystem.

Understanding Earth as a complex set of interacting living and nonliving elements is fundamental to knowing that human societies depend on diverse small and large ecosystems for food, water, and all other resources. People who regularly inquire about connections and relationships among life forms, ecosystems, and human societies possess an ecological perspective.

Complementing the Two Geographic Perspectives

Many perspectives supplement the two geographic perspectives and, when used appropriately, they can expand our understanding of spatial patterns and human-environment interactions. The geographic perspectives can be integrated with other disciplinary perspectives and with our own points of view to enrich and enlarge the understanding of people, places, and environments. Two other perspectives are of particular value to students of geography: the historical perspective and the economic perspective.

The Historical Perspective
All human events and activities have historic and geographic aspects. Central to historical inquiry are questions concerning chronology, the sequencing of events, relationships within and among societies over time, changes in cultures in various eras, and the changing relationships between civilizations and physical environments. A historical perspective enriches the geographic perspective by adding the essential questions of “When?” “Why then?” and “Why is the event significant?” These questions complement the study of whereness and consequently promote a deepened understanding of past and contemporary events, how and why places and regions form and change, and variations in human use of environments in different cultures and eras.

Understanding temporal patterns is a vital dimension of comprehending human experiences on Earth. People who ask questions about when events occurred and how events are related to each other over time use a historical perspective.

The Economic Perspective
Economics focuses on how people produce and exchange goods and services to fulfill such needs as food, shelter, transportation, and recreation. Earning a living, developing and trading resources, and inventing, producing, and distributing products and services are central to economics. Previously isolated economies are incorporated into the global economy through difficult transitions from subsistence to commercial activities. Economic transformations promote an increasing interdependence among all societies and cultures on Earth. Technological changes in transportation and communications accelerate and expand economic exchange between the peoples of the world. Local economies may be drastically altered by decisions made in distant places.

Understanding the integration of local, regional, and national economies with the global economy is critical to knowing how people interact. People who ask how diverse peoples earn a living and how peoples are connected through trade in goods and services apply an economic perspective.

Inquiry-Based Instruction

The five geographic skills are embedded in the inquiry approach to learning. Inquiry involves a process of exploring the natural or material world that leads to asking questions and making discoveries in the search for new understandings. Inquiry, as it relates to science education, should mirror as closely as possible the enterprise of doing real science. For more information on the inquiry approach, you may check online with the Institute for Inquiry Learning at www.exploratorium.edu/IFI/.

The National Geography Standards for Workshop 1

The National Geography Standards highlighted in this workshop include Standards 1, 2, 3, 4, 7, 8, 14, and 15. As you read, be thinking about how these standards apply in lessons you may have taught.

Standard 1: How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective.

Geographic information is compiled, organized, manipulated, stored, and made accessible in a great many ways. It is essential that students develop an understanding of those ways so they can make use of the information and learn the skills associated with developing and communicating information from a spatial perspective.

The study and practice of geography require the use of geographic representations, tools, and technologies. Geographic representations consist primarily of maps, and also include globes, graphs, diagrams, aerial and other photographs, and satellite-produced images. Tools and technologies consist primarily of reference works such as almanacs, gazetteers, geographic dictionaries, statistical abstracts, and other data compilations.

Maps are graphic representations of selected aspects of Earth's surface. They represent compilations of geographic information about selected physical and human features. Using point, line, and area symbols, as well as color, they show how those features are located, arranged, distributed, and related to one another. They range in appearance and purpose from a simple freehand line drawing of how to get to a friend's house to a complex multicolor depiction of atmospheric conditions used in weather forecasting. No single map can show everything, and the features depicted on each map are selected to fit a particular purpose. Maps can depict not only visible surface features such as rivers, seacoasts, roads, and towns but also underground features such as subway systems, tunnels, and geologic formations. They can depict abstract features such as political boundaries, population densities, and lines of latitude and longitude.

In the classroom, maps serve both as repositories of many kinds of geographic information and as an essential means of imparting that information to students. Maps constitute a critical element of geography education. However, they do have limitations. One major limitation is that it is not possible to accurately represent the round Earth on a flat surface without distorting at least one Earth property, such as distance, direction, or size and shape of land and water bodies. Therefore, different map projections are used to depict different Earth properties (e.g., equal area projections show landmasses in correct areal proportion to one another but with distortions of shape). No single map can accurately depict all Earth's properties, so it is essential that students know how to look at a given map and know which properties are rendered correctly and which are distorted.

As scale models, globes constitute the most accurate representation of Earth in terms of the properties of Earth's surface features; area, relative size and shape, scale and distance, and compass direction are proportionately and therefore correctly represented on globes. Globes present an essential overview of Earth, and they can be very useful in the teaching of such concepts as location, spatial patterns, Earth-Sun relationships, and time. However, globes have limitations: they are cumbersome to handle and store, small in scale, and only half of Earth can be observed at once.

In addition to maps and globes, graphs, diagrams, aerial and other photographs, and satellite-produced images also provide valuable information about spatial patterns on Earth. They are very diversified in the kinds of information they present and, under certain circumstances, have classroom value as both supplements to and substitutes for globes and maps. However, they also have limitations: for instance, they may not be immediately understandable to students, who may need special instruction in their use.

The tools and technologies used in geography encompass a great variety of reference works, ranging from encyclopedias and other multivolume publications covering many topics to single reports on specialized subjects. Some of these works are in narrative form; some are primarily compilations of data represented in tabular form. Some are easy to understand and use; some are not. Students need to develop an understanding of the kinds of reference works that are available to them, as well as learn how to obtain information from the works, how to gauge the general reliability of that information, and how to convert information from one form to another (e.g., take data from a table and present it in a written narrative).

Traditionally, reference works have been available solely in printed form. Currently, however, more and more of them are also being made available in the form of computer-based databases and computer-based information systems. This development is a result of computer systems becoming an essential tool for storing, analyzing, and presenting spatial information. Because of their speed and flexibility, such systems enable the geographically informed person to explore, manipulate, and assess spatial data far more effectively than do conventional printed materials (see Geography for Life, Appendix E). Furthermore, current developments in multimedia techniques, such as animation, sound, and interactive learning procedures, promise an even more flexible and creative approach to geographic learning.

Throughout their K-12 schooling, students should continue to have direct experience with a wide variety of geographic representations, especially maps. Maps can become increasingly abstract with each succeeding grade level, reflecting the developmental changes in students' abilities to represent and manipulate spatial and symbolic information. In the early grades, students should come to see maps, like the written word, as a source of information about their world. They should be given opportunities to read and interpret different kinds of maps and to create maps of their classroom, school, and neighborhood using various media (e.g., pencils, cutouts). Subsequent experiences in map reading and mapmaking should become more sophisticated and abstract as students develop a more comprehensive understanding of the knowledge, skills, and perspectives involved in maps and mapping activities.

In addition, students should be given an opportunity to become familiar with computer systems and computer-based geographic information systems. As such systems become increasingly common in the home, school, and workplace, for many different purposes, people will learn to use them as comfortably and as effectively as they have traditionally used printed materials. Therefore, it is essential that students of geography be exposed to as many forms of geographic data processing as possible and come to understand the role of computer systems in both the study and practice of geography.

Knowing how to identify, access, evaluate, and use all of these geographic resources will ensure students a rich school experience in geography and the prospect of having an effective array of problem-solving and decision-making skills for use in both their other educational pursuits and their adult years.

Standard 2: How to use mental maps to organize information about people, places, and environments in a spatial context.

To be geographically informed, a person must keep in mind a lot of information about people, places, and environments, and must be able to organize this information in the appropriate spatial contexts. A very effective way of doing this is to create and use what can be called "mental maps." Such a map is an individual's internalized representation of some aspect or aspects of Earth's surface. It represents what the person knows about the locations and characteristics of places at a variety of scales (local to global), from the layout of the student's bedroom to the distribution of oceans and continents on the surface of the Earth. These maps in the mind provide students with an essential means of making sense of the world, and of storing and recalling information about the shapes and patterns of the physical and human features of Earth. Learning how to create and use mental maps, therefore, is a fundamental part of the process of becoming geographically informed.

Mental maps have several distinguishing characteristics:

  • Mental maps are personal and idiosyncratic and are usually a mixture of both objective knowledge and subjective perceptions. They contain objective and precise knowledge about the location of geographic features such as continents, countries, cities, mountain ranges, and oceans. They also contain more subjective and less- precise information, such as impressions of places, rough estimates of relative size, shape, and location, and a general sense of certain connections between places, as well as priorities that reflect the mapmaker's own predilections.
  • Mental maps are used in some form by all people throughout their lives. Such maps enable people to know what routes to take when traveling, comprehend what others say or write about various places, and develop an understanding of the world.
  • Mental maps represent ever-changing summaries of spatial knowledge and serve as indicators of how well people know the spatial characteristics of places. People develop and refine their mental maps both through personal experience and through learning from teachers and the media. They refine at least some of their maps to ever-higher levels of completeness and accuracy, and they continue to add information so that the maps reflect a growing understanding of a changing world. Critical geographic observation is essential to this development and refinement process, because mental maps reflect people's skill in observing and thinking about the world in spatial terms (and have nothing to do with their ability to draw).

As students read, hear, observe, and think more about the world around them, they can add more detail and structure to their maps. As students get older, their mental maps accumulate multiple layers of useful information and this growth in complexity and utility can provide them with a sense of satisfaction as more places and events in the world can be placed into meaningful spatial contexts.

If geography is to be useful in creating a framework for understanding the world—past, present, and future—then coherent mental maps must take shape and become increasingly refined as students progress through their school years. Students should be encouraged to develop and update their mental maps to ensure that they continue to have essential knowledge of place location, place characteristics, and other information that will assist them in personal decision-making and in establishing a broad-based perception of Earth from a local to a global perspective. In addition, they need to understand that developing mental maps is a basic skill for everyone who wants to engage in a lifetime of geographic understanding.

Standard 3: How to analyze the spatial organization of people, places, and environments on the Earth's surface.

Thinking in spatial terms is essential to knowing and applying geography. It enables students to take an active, questioning approach to the world around them, and to ask what, where, when, and why questions about people, places, and environments. Thinking spatially enables students to formulate answers to critical questions about past, present, and future patterns of spatial organization; to anticipate the results of events in different locations; and to predict what might happen given specific conditions. Spatial concepts and generalizations are powerful tools for explaining the world at all scales, local to global. They are the building blocks on which geographic understanding develops.

Thinking in spatial terms means having the ability to describe and analyze the spatial organization of people, places, and environments on Earth's surface. It is an ability that is central to a person being geographically literate.

Geographers refer to both the features of Earth's surface and the activities that take place on Earth's surface as phenomena. The phenomena may be physical (topography, streams and rivers, climates, vegetation types, soils), human (towns and cities, population, highways, trade flows, the spread of a disease, national parks), or physical and human taken together (beach resorts in relation to climate, topography, or major population centers). The location and arrangement of both physical and human phenomena form regular and recurring patterns.

The description of a pattern of spatial organization begins by breaking it into its simplest components: points, lines, areas, and volumes. These four elements describe the spatial properties of objects: a school can be thought of as a point connected by roads (which are lines) leading to nearby parks and neighborhoods (which are areas), whereas a lake in a park can be thought of as a volume. The next step in the descriptive process is to use such concepts as location, distance, direction, density, and arrangement (linear, grid-like, random) to capture the relationships between the elements of the pattern. Thus the U.S. interstate highway system can be described as lines connecting points over an area—the arrangement is partly grid-like (with north-south and east-west routes as in the central United States) and partly radial or star-shaped (as in the highways centered on Atlanta)—and the pattern of interstates is denser in the East than it is in the West.

The analysis of a pattern of spatial organization proceeds with the use of such concepts as movement and flow, diffusion, cost of distance, hierarchy, linkage, and accessibility to explain the reasons for patterns and the functioning of the world. In the case of a physical pattern, such as a river system, there is a complex hierarchical arrangement linking small streams with small drainage basins and large rivers with drainage basins that are the sum total of all of the smaller drainage basins. There are proportional spatial relationships between stream and river length, width, volume, speed, and drainage basin area. The gradual changes that can occur in these properties of a river system are related to climate, topography, and geology.

Central to geography is the belief that there is pattern, regularity, and reason to the locations of physical and human phenomena on Earth's surface and that there are spatial structure and spatial processes that give rise to them. Students must be encouraged to think about all aspects of the spatial organization of their world. Understanding the distribution and arrangement of the Earth's physical and human features depends on analyzing data gathered from observation and field study, working with maps and other geographic representations, and posing geographic questions and deriving geographic answers.

Spatial relationships, spatial structure, and spatial processes are simple to understand, despite their apparent unfamiliarity. For example, the spatial organization of human settlement on Earth's surface is generally a pattern of a few large cities, which are widely spaced and many smaller towns, which are closer together. A comparative analysis of those cities and towns shows that cities offer a wide range of goods and services whereas small towns offer fewer goods and services. Taken together, the description and the analysis explain why consumers shop where they do, why they often buy different products at different locations, and also why changes occur in this spatial pattern.

Understanding patterns of spatial organization enables the geographically informed person to answer three fundamental geographic questions: Why are these phenomena located in these places? How did they get there? Why is this pattern significant? Description and analysis of patterns of spatial organization must occur at scales ranging from local to global.

Students confront a world that is increasingly interdependent. Widely separated places are interconnected as a consequence of improved transportation and communication networks. Human decisions at one location have physical impacts at another location. (For example, the decision to burn coal rather than oil in a power plant may result in acid rain damaging vegetation hundreds of miles away.)

Understanding such spatial linkages requires that students become familiar with a range of spatial concepts and models that can be used to describe and analyze patterns of spatial organization. This knowledge can be grounded in the students' own immediate experiences, and yet it will give the students the power to understand the arrangement of physical and human geographic phenomena anywhere on Earth.

Standard 4: The physical and human characteristics of places.

People's lives are grounded in particular places. We come from a place, we live in a place, and we preserve and exhibit fierce pride over places. Our sense of self is intimately entwined with that of place. Who we are is often inseparable from where we are. Places are human creations and the geographically informed person must understand the genesis, evolution, and meaning of places.

Places are parts of Earth's space, large or small, that have been endowed with meaning by humans. They include continents, islands, countries, regions, states, cities, neighborhoods, villages, rural areas, and uninhabited areas. They usually have names and boundaries. Each place possesses a distinctive set of tangible and intangible characteristics that helps to distinguish it from other places. Places are characterized by their physical and human properties. Their physical characteristics include climate, landforms, soils, hydrology, vegetation, and animal life. Their human characteristics include language, religion, political systems, economic systems, population distribution, and quality of life.

Places change over time as both physical and human processes operate to modify Earth's surface. Few places remain unchanged for long and these changes have a wide range of consequences. As knowledge, ideologies, values, resources, and technologies change, people make place-altering decisions about how to use land, how to organize society, and ways in which to relate (such as economically or politically) to nearby and distant places. Out of these processes emerge new places, with existing places being reorganized and expanded, other places declining, and some places disappearing. Places change in size and complexity and in economic, political, and cultural importance as networks of relationships between places are altered through population expansion, the rise and fall of empires, changes in climate and other physical systems, and changes in transportation and communication technologies. A place can be dramatically altered by events both near and far.

Knowing how and why places change enables people to understand the need for knowledgeable and collaborative decision-making about where to locate schools, factories, and other things and how to make wise use of features of the physical environment such as soil, air, water, and vegetation. Knowing the physical and human characteristics of their own places influences how people think about who they are, because their identity is inextricably bound up with their place in life and the world. Personal identity, community identity, and national identity are rooted in place and attachment to place. Knowing about other places influences how people understand other peoples, cultures, and regions of the world. Knowledge of places at all scales, local to global, is incorporated into people's mental maps of the world.

Students need an understanding of why places are the way they are, because it can enrich their own sense of identity with a particular place and enable them to comprehend and appreciate both the similarities and differences of places around their own community, state, country, and planet.

Standard 7: The physical processes that shape the patterns of Earth's surface.

Physical processes create, maintain, and modify Earth's physical features and environments. Because the physical environment is the essential background for all human activity on Earth, the geographically informed person must understand the processes that produce those features.

Physical processes can be grouped into four categories: those operating in the atmosphere (i.e., climate and meteorology), those operating in the lithosphere (e.g., plate tectonics, erosion, and soil formation), those operating in the hydrosphere (e.g., the circulation of the oceans and the hydrologic cycle), and those operating in the biosphere (e.g., plant and animal communities and ecosystems).

By understanding the interaction within and between these categories of physical processes, the geographically informed person can pose and answer certain fundamental questions: What does the surface of Earth look like? How have its features been formed? What is the nature of these features and how do they interact? How and why are they changing? What are the spatially distinct combinations of environmental features? How are these environmental features related to past, present, and prospective human uses of Earth? The answers to these questions lead to an understanding of how Earth serves as the home of all plants and animals, including humans.

Processes shape and maintain the physical environment. Therefore it is vital that students appreciate the complex relationships between processes and resultant features, and how these relationships give rise to patterns of spatial organization. For example, in a region such as southern California, the physical landscape is constantly reshaped by a complex set of interacting physical processes: earthquakes, coastal erosion, land subsidence owing to subsurface oil and water extraction, flash floods and landslides caused by heavy rainfall in the spring, and drought and the loss of chaparral vegetation from fire in the dry summer weeks. In turn, these processes show chains of interaction: the chaparral vegetation is the biosphere's response to the climate and soil. Given the expected variations in rainfall in this Mediterranean climate regime, the chaparral becomes dormant and is prone to fire; however, clearance of the chaparral vegetation, especially in the canyons of steep hills, exposes the surface to flash flooding and soil erosion.

Five basic ideas help to explain the interactions and effects of physical processes. These are known as system, boundary, force, state of equilibrium, and threshold. A system is a collection of elements that are mutually connected and therefore influence one another to form a unified whole (e.g., the hydrologic cycle). Each system has boundaries, either real or arbitrary, within which it operates. Some forces, such as gravity and weather, activate and drive processes; other forces, such as friction, resist change and act to maintain the status quo. Systems exist in different states. When a system is in equilibrium, driving forces such as gravity and resisting forces such as friction are in balance. However, when a threshold—the point at which change may occur—is reached, adjustment takes place. For example, an avalanche occurs when gravity, acting on deep layers of snow, overcomes the friction that was holding the snow mass in place (i.e., a state of equilibrium gives way when a threshold is reached). After the avalanche a new state of equilibrium is established.

It is essential that students understand the physical processes that act upon Earth and that such processes affect the choices made by people in different regions of the United States. Knowledge of these processes is required for dealing with such commonplace issues as: evaluating locations of relative safety in an earthquake-prone region; purchasing a home in a floodplain; coping with the threat of sinkholes and subsidence in a landscape underlain by limestone deposits; and building a house in an area that has shrink-swell clay soils.

It is also essential that students learn to make intelligent predictions about future events and evaluate the short- and long-term effects of physical events on places and regions. Evaluating reports of world climate change requires knowing the factors that affect climate and weather in general and how the natural environment functions in particular regions. Climate and weather affect more than just personal decision-making on a daily basis. They are major factors in understanding world economic conditions over longer periods. Many important natural resources are formed by physical processes that occur in relatively few places on Earth. Understanding physical processes and the patterns of resources they produce is vital to understanding not only the physical geography of Earth's surface but also the strategic relationships between nations and world trade patterns.

Understanding physical processes enables the geographically informed person to link the personal with the societal, the short term with the long term, and the local with the global dimensions of Earth.

The context of migration varies from voluntary and discretionary (the search for a better place to live), to voluntary but unavoidable (the search for a place to live), to involuntary and unavoidable (the denial of the right to choose a place to live).

In the two voluntary contexts, migration often results from the weighing of factors at the point of origin and at potential destinations against the costs (financial and emotional) of moving. "Pull" factors may make another place seem more attractive and therefore influence the decision to move. Other factors are unpleasant enough to "push" the migrant out of the local setting and toward another area. These factors reflect people's objective knowledge of places and also their secondhand impressions. As a consequence, many countries have experienced waves of people going from settled areas to new lands in the interior (e.g., the westward movement in the United States in the nineteenth century and the move from the southeast coast to the interior of Brazil starting in the 1960s, when the new capital city of Brasilia was built).

Voluntary and unavoidable migration occurs when much of a region's or country's population is impelled into migration streams, such as the millions of Irish who fled to the United States in the 1840s because of the potato famine or the millions of Somalis, Sudanese, and Rwandans who moved in the 1990s because of drought, famine, and civil war. However, some migrations are forced and involuntary. Such was the case with African Americans who were taken to North and South America in the seventeenth, eighteenth, and nineteenth centuries to work as slave laborers on sugar, cotton, and tobacco plantations.

Demographic shifts rearrange patterns of population and create new human landscapes. Natural increase, war, famine, and disease play decisive roles in influencing why many people live where they do. Migration sets people in motion as they leave one place, strike out for a second, and possibly settle in a third. Intervening obstacles influence the patterns of migration. Physical barriers such as deserts, mountains, rivers, and seas or cultural barriers such as political boundaries, languages, economic conditions, and cultural traditions determine how people move and where they settle.

It is essential that students develop an understanding of the dynamics of population characteristics, distributions, and migration, and in particular of how population distribution (in terms of size and characteristics) is linked to the components of fertility, mortality, and mobility.

Standard 8: The characteristics and spatial distribution of ecosystems on Earth's surface.

Ecosystems are a key element in the viability of planet Earth as human home. Populations of different plants and animals that live and interact together are called a community. When such a community interacts with the other three components of the physical environment—atmosphere, hydrosphere, and lithosphere—the result is an ecosystem. The cycles of flows and interconnections—physical, chemical, and biological—between the parts of ecosystems form the mosaic of Earth's environments. The geographically informed person needs to understand the spatial distribution, origins, functioning, and maintenance of different ecosystems and to comprehend how humans have intentionally or inadvertently modified these ecosystems.

Ecosystems form distinct regions on Earth's surface, which vary in size, shape, and complexity. They exist at a variety of scales, from small and very localized areas (e.g., a single stand of oak trees or a clump of xerophytic grasses) to larger areas with precise geographic boundaries (e.g., a pond, desert biome, island, or beach). Larger-scale ecosystems can form continent-wide belts, such as the tundra, taiga, and steppe of northern Asia. The largest ecosystem is the planet itself.

All elements of the environment, physical and human, are part of several different but nested ecosystems. Ecosystems, powered by solar energy, are dynamic and ever-changing. Changes in one ecosystem ripple through others with varying degrees of impact. As self-regulating open systems that maintain flows of energy and matter, they naturally move toward maturity, stability, and balance in the absence of major disturbances. In ecological terms, the physical environment can be seen as an interdependent web of production and consumption cycles. The atmosphere keeps plants and animals alive through solar energy, chemical exchanges (e.g., nitrogen-fixing and photosynthesis), and the provision of water. Through evapotranspiration the atmosphere and plants help to purify water. Plants provide the energy to keep animals alive either directly through consumption or indirectly through their death and decay into the soil, where the resultant chemicals are taken up by new plants. Soils keep plants and animals alive and work to cleanse water. The root systems of plants and the mechanical and chemical effects of water percolating through bedrock create new soil layers. Ecosystems therefore help to recycle chemicals needed by living things to survive, redistribute waste products, control many of the pests that cause disease in both humans and plants, and offer a huge pool of resources for humans and other living creatures.

However, the stability and balance of ecosystems can be altered by large-scale natural events such as El Niño, volcanic eruptions, fire, or drought. But ecosystems are more drastically transformed by human activities. The web of ecological interdependency is fragile. Human intervention can shatter the balance of energy production and consumption. For example, the overgrazing of pasturelands, coupled with a period of drought, can lead to vegetation loss, the exposure of topsoil layers, and massive soil erosion (as occurred in the 1930s Dust Bowl); tropical forest clear-cutting can lead to soil erosion and ecological breakdown, as is currently occurring in Amazonia; and the construction of oil pipelines in tundra environments can threaten the movements of the caribou herds on which indigenous Inuit populations depend.

By knowing how ecosystems operate and change, students are able to understand the basic principles that should guide programs for environmental management. Students can understand the ways in which they are dependent on the living and nonliving systems of Earth for their survival. Knowing about ecosystems will enable them to learn how to make reasoned decisions, anticipate the consequences of their choices, and assume responsibility for the outcomes of their choices about the use of the physical environment. It is important that students become well-informed regarding ecosystem issues so they can evaluate conflicting points of view on the use of natural resources. The degree to which present and future generations understand their critical role in the natural functioning of ecosystems will determine in large measure the quality of human life on Earth.

Standard 14: How human actions modify the physical environment.

Many of the important issues facing modern society are the consequences—intended and unintended, positive and negative—of human modifications of the physical environment. So it is that the daily news media chronicle such things as the building of dams and aqueducts to bring water to semiarid areas; the loss of wildlife habitat; the reforestation of denuded hills; the depletion of the ozone layer; the ecological effects of acid rain; the reduction of air pollution in certain urban areas; and the intensification of agricultural production through irrigation.

Environmental modifications have economic, social, and political implications for most of the world's people. Therefore, the geographically informed person must understand the reasons for and consequences of human modifications of the environment in different parts of the world.

Human adaptation to and modification of physical systems are influenced by the geographic context in which people live, their understanding of that context, and their technological ability and inclination to modify it to suit their changing need for things such as food, clothing, water, shelter, energy, and recreational facilities. In meeting their needs, they bring knowledge and technology to bear on physical systems.

Consequently, humans have altered the balance of nature in ways that have brought economic prosperity to some areas and created environmental dilemmas and crises in others. Clearing land for settlement, mining, and agriculture provides homes and livelihoods for some but alters physical systems and transforms human populations, wildlife, and vegetation. The inevitable by-products—garbage, air and water pollution, hazardous waste, the overburden from strip mining—place enormous demands on the capacity of physical systems to absorb and accommodate them.

The intended and unintended impacts on physical systems vary in scope and scale. They can be local and small-scale (e.g., the terracing of hillsides for rice growing in the Philippines and acid stream pollution from strip mining in eastern Pennsylvania); regional and medium scale (e.g., the creation of agricultural polderlands in the Netherlands and of an urban heat island with its microclimatic effects in Chicago); or global and large-scale (e.g., the clearing of the forests of North America for agriculture or the depletion of the ozone layer by chlorofluorocarbons).

Students must understand both the potential of a physical environment to meet human needs and the limitations of that same environment. They must be aware of and understand the causes and implications of different kinds of pollution, resource depletion, and land degradation and the effects of agriculture and manufacturing on the environment. They must know the locations of regions vulnerable to desertification, deforestation, and salinization, and be aware of the spatial impacts of technological hazards such as photochemical smog and acid rain. Students must be aware that current distribution patterns for many plant and animal species are a a result of relocation diffusion by humans.

In addition, students must learn to pay careful attention to the relationships between population growth, urbanization, and the resultant stress on physical systems. The process of urbanization affects wildlife habitats, natural vegetation, and drainage patterns. Cities create their own microclimates and produce large amounts of solid waste, photochemical smog, and sewage. A growing world population stimulates increases in agriculture, urbanization, and industrialization. These processes expand demands on water resources, resulting in unintended environmental consequences that can alter water quality and quantity.

Understanding global interdependence begins with an understanding of global dependence: the modification of Earth's surface to meet human needs. When successful, the relationship between people and the physical environment is adaptive; when the modifications are excessive, the relationship is maladaptive. Increasingly, students will be required to make decisions about relationships between human needs and the physical environment. They will need to be able to understand the opportunities and limitations presented by the geographical context and to set those contexts within the local to global continuum.

Standard 15: How physical systems affect human systems.

No matter what the spatial scale, Earth's surface presents a picture of physical diversity in terms of soils, climates, vegetation, and topography. That diversity offers a range of environmental contexts for people. The geographically informed person must understand how humans are able to live in various kinds of physical environments—not only those of the familiar mid-latitudes but also those that seem less conducive to intensive settlement such as the Arctic tundra and the Equatorial rain forest—and the role physical features of those environments play in shaping human activities.

To live in any given physical environment, humans must develop patterns of spatial organization, which take advantage of opportunities offered and avoid or minimize the effects of limitations. Physical systems and environmental characteristics do not, by themselves, determine the pattern of human activity. If the incentives are great enough, settlement is possible, although at great cost and risk. The trans-Alaska oil pipeline and construction techniques used in tundra-area settlements are evidence of the extent of human ingenuity. However, the environment does place limitations on human societies. (For example, a glaciated region with its complex of features—thin, rocky water-logged soils and unique landforms—offers few opportunities for commercial agriculture.)

A central concept is the idea of carrying capacity: the maximum, sustained level of use of an environment that is possible without incurring significant environmental destruction. Environments vary in their carrying capacity, and people's failure to understand it—or their inability to live within it—can lead to environmental disaster. Cyclical environmental change, especially in semiarid environments, can pose particular problems for human use of that environment and can lead to desertification, famine, and mass migration, as has occurred in the Sahel of north-central Africa. The relationship between any environment and its inhabitants is mediated by decisions about how much to consume and in what ways to consume. Energy conservation, water conservation, and recycling can have significant effects on patterns of environmental use.

In modern times human have used technology as a means of reducing the potential effect of physical systems on human activity. In the United States, for example, the widespread introduction of air-conditioning has allowed people to relocate to the South and Southwest, regions previously considered less suited to settlement. And in various regions of Earth, use of the airplane has made it possible to establish settlements and industries in hitherto-inaccessible places. However, the use of technology to overcome physical impediments to human activity can also have wide-ranging and sometimes unexpected consequences. For instance, the attempt to control rivers by building dams and dredging waterways to prevent destructive and life-threatening floods can also lead to diminished soil replenishment, increased water salinity, reduced flow of sediment to oceans, and increased riverbank erosion.

In addition to carrying-capacity limitations, the physical environment often imposes significant costs on human society. Natural hazards are defined as processes or events in the physical environment that are not caused by humans but whose consequences can be harmful. They cost the United States billions of dollars each year. Hurricanes, earthquakes, tornadoes, volcanoes, storms, floods, forest fires, and insect infestations are events that are not preventable and whose precise location, timing, and magnitude are not predictable. Their negative consequences can be reduced by understanding the potential vulnerability of different groups of people and by implementing a variety of strategies such as improved building design, land-use regulation, warning systems, and public education.

Whether the issue is the mitigation of a natural hazard or recognition of carrying capacity, students need to understand the characteristics and spatial properties of the physical environment. It is essential that they be able to translate an understanding of the physical processes and patterns that shape Earth's surface into a picture of that surface as a potential home for people. That home can hold only so many people or be used only in certain ways without incurring costs. Judgment as to the acceptability of those costs requires an understanding of environmental opportunities and constraints.

The above material is from Geography for Life: The National Geography Standards, 1994, The Geography Education Standards Project. Reprinted with the permission of the National Geographic Society.