Education theory
Encyclopedia
Educational theory can refer to either speculative educational thought in general or to a theory of education as something that guides, explains, or describes educational practice.

In terms of speculative thought, its history began with classical Greek philosophers and sophists, and today it is a term for reflective theorizing about pedagogy
Pedagogy
Pedagogy is the study of being a teacher or the process of teaching. The term generally refers to strategies of instruction, or a style of instruction....

, andragogy
Andragogy
Andragogy consists of learning strategies focused on adults. It is often interpreted as the process of engaging adult learners with the structure of learning experience. The term ‘andragogy’ has been used in different times and countries with various connotations. Nowadays there exist mainly three...

, curriculum
Curriculum
See also Syllabus.In formal education, a curriculum is the set of courses, and their content, offered at a school or university. As an idea, curriculum stems from the Latin word for race course, referring to the course of deeds and experiences through which children grow to become mature adults...

, learning
Learning theory (education)
In psychology and education, learning is commonly defined as a process that brings together cognitive, emotional, and environmental influences and experiences for acquiring, enhancing, or making changes in one's knowledge, skills, values, and world views . Learning as a process focuses on what...

, and education policy
Policy
A policy is typically described as a principle or rule to guide decisions and achieve rational outcome. The term is not normally used to denote what is actually done, this is normally referred to as either procedure or protocol...

, organization and leadership
Leadership
Leadership has been described as the “process of social influence in which one person can enlist the aid and support of others in the accomplishment of a common task". Other in-depth definitions of leadership have also emerged.-Theories:...

. Educational thought is informed by various strands of history
History
History is the discovery, collection, organization, and presentation of information about past events. History can also mean the period of time after writing was invented. Scholars who write about history are called historians...

, philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

, sociology
Sociology
Sociology is the study of society. It is a social science—a term with which it is sometimes synonymous—which uses various methods of empirical investigation and critical analysis to develop a body of knowledge about human social activity...

, critical theory
Critical theory
Critical theory is an examination and critique of society and culture, drawing from knowledge across the social sciences and humanities. The term has two different meanings with different origins and histories: one originating in sociology and the other in literary criticism...

, and psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

, among other disciplines.

On the other hand, a theory of education can be "normative (or prescriptive) as in philosophy, or descriptive as in science." In the first case, a theory means a postulation about what ought to be. It provides the "goals, norms, and standards for conducting the process of education." In the second case, it means "an hypothesis or set of hypotheses that have been verified by observation and experiment." Whereas a normative educational theory provided by a philosopher might offer goals of education, descriptive "theory provides concrete data that will help realize more effectively the goals suggested by the philosopher." A descriptive theory of education can be thought of as a conceptual scheme that ties together various "otherwise discrete particulars. . .For example, a cultural theory of education shows how the concept of culture can be used to organize and unify the variety of facts about how and what people learn." Likewise, for example, there is the behaviorist theory of education
Behaviorism
Behaviorism , also called the learning perspective , is a philosophy of psychology based on the proposition that all things that organisms do—including acting, thinking, and feeling—can and should be regarded as behaviors, and that psychological disorders are best treated by altering behavior...

 that comes from educational psychology
Educational psychology
Educational psychology is the study of how humans learn in educational settings, the effectiveness of educational interventions, the psychology of teaching, and the social psychology of schools as organizations. Educational psychology is concerned with how students learn and develop, often focusing...

 and the functionalist theory of education that comes from sociology of education
Sociology of education
The sociology of education is the study of how public institutions and individual experiences affect education and its outcomes. It is most concerned with the public schooling systems of modern industrial societies, including the expansion of higher, further, adult, and continuing...

.

In general, there are currently three main ways in which the term "theory" is used in education:
  • the obverse of practice--theorizing is thinking and reflecting as opposed to doing;
  • a generalizing or explanatory model of some kind, e.g., a specific learning theory like constructivism
    Constructivism (learning theory)
    Constructivism is a theory of knowledge that argues that humans generate knowledge and meaning from an interaction between their experiences and their ideas. During infancy, it was an interaction between human experiences and their reflexes or behavior-patterns. Piaget called these systems of...

    ;
  • a body of knowledge--these may or may not be associated with particular explanatory models. To theorize is to develop these bodies of knowledge.

Educational thought

Educational thought is not necessarily concerned with the construction of theories as much as it is the "reflective examination of educational issues and problems from the perspective of diverse disciplines."

Normative theories of education

Normative theories of education provide the norms, goals, and standards of education.

Educational philosophies

"Normative philosophies or theories of education may make use of the results of [philosophical thought] and of factual inquiries about human beings and the psychology of learning, but in any case they propound views about what education should be, what dispositions it should cultivate, why it ought to cultivate them, how and in whom it should do so, and what forms it should take. In a full-fledged philosophical normative theory of education, besides analysis of the sorts described, there will normally be propositions of the following kinds:
1. Basic normative premises about what is good or right;
2. Basic factual premises about humanity and the world;
3. Conclusions, based on these two kinds of premises, about the dispositions education should foster;
4. Further factual premises about such things as the psychology of learning and methods of teaching; and
5. Further conclusions about such things as the methods that education should use."

Examples of the purpose of schools include: develop reasoning about perennial questions, master the methods of scientific inquiry, cultivate the intellect, create change agents, develop spirituality, and model a democratic society

Common educational philosophies include: educational perennialism
Educational perennialism
Perennialists believe that one should teach the things that one deems to be of everlasting importance to all people everywhere. They believe that the most important topics develop a person. Since details of fact change constantly, these cannot be the most important. Therefore, one should teach...

, educational progressivism
Educational progressivism
Progressive education is a pedagogical movement that began in the late nineteenth century and has persisted in various forms to the present. More recently, it has been viewed as an alternative to the test-oriented instruction legislated by the No Child Left Behind educational funding act...

, educational essentialism
Educational essentialism
Educational essentialism is an educational philosophy whose adherents believe that children should learn the traditional basic subjects thoroughly and rigorously. In this philosophical school of thought, the aim is to instill students with the "essentials" of academic knowledge, enacting a...

, critical pedagogy
Critical pedagogy
Critical pedagogy is a philosophy of education described by Henry Giroux as an "educational movement, guided by passion and principle, to help students develop consciousness of freedom, recognize authoritarian tendencies, and connect knowledge to power and the ability to take constructive...

, Montessori education
Montessori method
Montessori education is an educational approach developed by Italian physician and educator Maria Montessori. Montessori education is practiced in an estimated 20,000 schools worldwide, serving children from birth to eighteen years old.-Overview:...

, Waldorf education, and democratic education
Democratic education
Democratic education is a theory of learning and school governance in which students and staff participate freely and equally in a school democracy...

.

Curriculum theory

Normative theories of curriculum
Curriculum theory
Curriculum theory is the theory of the development and enactment of curriculum. Within the broad field of curriculum studies, it is both a historical analysis of curriculum and a way of viewing current educational curriculum and policy decisions...

 aim to "describe, or set norms, for conditions surrounding many of the concepts and constructs" that define curriculum
Curriculum
See also Syllabus.In formal education, a curriculum is the set of courses, and their content, offered at a school or university. As an idea, curriculum stems from the Latin word for race course, referring to the course of deeds and experiences through which children grow to become mature adults...

. These normative propositions are different than the ones above in that normative curriculum theory is not necessarily untestable. A central question asked by normative curriculum theory is: given a particular educational philosophy, what is worth knowing and why? Some examples are: a deep understanding of the Great Books
Great Books
Great Books refers primarily to a group of books that tradition, and various institutions and authorities, have regarded as constituting or best expressing the foundations of Western culture ; derivatively the term also refers to a curriculum or method of education based around a list of such books...

, direct experiences driven by student interest, a superficial understanding of a wide range knowledge (e.g., Core knowledge
Core Knowledge
Core Knowledge refers to a current textbook series originally written by a collective of former top Year 12 South Australian students of the same name for South Australian Certificate of Education students...

), social and community problems and issues, knowledge and understanding specific to cultures and their achievements (e.g., African-Centered Education
African-Centered Education
Afrocentric education is education designed to empower African people. A central premise behind it is that many Africans have been subjugated by limiting their awareness of themselves and indoctrinating them with ideas that work against them. To control a people's culture is to control their tools...

)

Descriptive theories of education

Descriptive theories of education provide descriptions or explanations of the processes of education.

Curriculum theory

Descriptive theories of curriculum explain how curricula "benefit or harm all publics it touches". One descriptive concept from curriculum theory is that of the hidden curriculum
Hidden curriculum
Hidden curriculum, in general terms, is “some of the outcomes or by-products of schools or of non-school settings, particularly those states which are learned but not openly intended.” However, a variety of definitions have been developed based on the broad range of perspectives of those who study...

, which is “some of the outcomes or by-products of school
School
A school is an institution designed for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is commonly compulsory. In these systems, students progress through a series of schools...

s or of non-school settings, particularly those states which are learned but not openly intended.”

Instructional theory

Instructional theories focuses on the methods of instruction for teaching curricula
Curriculum
See also Syllabus.In formal education, a curriculum is the set of courses, and their content, offered at a school or university. As an idea, curriculum stems from the Latin word for race course, referring to the course of deeds and experiences through which children grow to become mature adults...

. Theories include the methods of: autonomous learning, coyote teaching
Coyote teaching
Coyote teaching is a method of teaching and mentoring made popular by Tom Brown, Jr. and Jon Young. A coyote teacher never gives direct answers, and answers questions with questions, inspiring the student to dig deeper into the lessons and search for embedded or connected lessons...

, inquiry-based instruction
Inquiry-based instruction
Inquiry-based instruction is a teaching technique in which teachers create situations in which students are to solve problems. Lessons are designed so that students make connections to previous knowledge, bring their own questions to learning, investigate to satisfy their own questions and design...

, lecture
Lecture
thumb|A lecture on [[linear algebra]] at the [[Helsinki University of Technology]]A lecture is an oral presentation intended to present information or teach people about a particular subject, for example by a university or college teacher. Lectures are used to convey critical information, history,...

, maturationism
Maturationism
Maturationism is an early childhood educational philosophy that sees the child as a growing organism and believes that the role of education is to passively support this growth rather than actively fill the child with information....

, socratic method
Socratic method
The Socratic method , named after the classical Greek philosopher Socrates, is a form of inquiry and debate between individuals with opposing viewpoints based on asking and answering questions to stimulate critical thinking and to illuminate ideas...

, outcome-based education
Outcome-based education
Outcome-based education is a recurring education reform model. It is a student-centered learning philosophy that focuses on empirically measuring student performance, which are called outcomes. OBE contrasts with traditional education, which primarily focuses on the resources that are available...

, taking children seriously
Taking Children Seriously
Taking Children Seriously is a parenting movement and educational philosophy whose central idea is that it is possible and desirable to raise and educate children without either doing anything to them against their will, or making them do anything against their will.It was founded in 1994 as an...

, transformative learning
Transformative learning
At the core of Transformative Learning Theory, is the process of "perspective transformation", with three dimensions: psychological , convictional , and behavioral ....


The nature of the learner and of learning

Philosophical Anthropology

Philosophical anthropology
Philosophical anthropology
Philosophical anthropology is a discipline dealing with questions of metaphysics and phenomenology of the human person, and interpersonal relationships. It is the attempt to unify disparate ways of understanding behaviour of humans as both creatures of their social environments and creators of...

 is the philosophical
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

 study of human nature
Human nature
Human nature refers to the distinguishing characteristics, including ways of thinking, feeling and acting, that humans tend to have naturally....

. In terms of learning, examples of descriptive theories of the learner are: a mind, soul, and spirit capable of emulating the Absolute Mind (Idealism
Idealism
In philosophy, idealism is the family of views which assert that reality, or reality as we can know it, is fundamentally mental, mentally constructed, or otherwise immaterial. Epistemologically, idealism manifests as a skepticism about the possibility of knowing any mind-independent thing...

); an orderly, sensing, and rational being capable of understanding the world of things (Realism
Realism
Realism, Realist or Realistic are terms that describe any manifestation of philosophical realism, the belief that reality exists independently of observers, whether in philosophy itself or in the applied arts and sciences. In this broad sense it is frequently contrasted with Idealism.Realism in the...

), a rational being with a soul modeled after God and who comes to know God through reason and revelation (Neo-Thomism), an evolving and active being capable of interacting with the environment (Pragmatism
Pragmatism
Pragmatism is a philosophical tradition centered on the linking of practice and theory. It describes a process where theory is extracted from practice, and applied back to practice to form what is called intelligent practice...

), a fundamentally free and individual being who is capable of being authentic through the making of and taking responsibility for choices (Existentialism
Existentialism
Existentialism is a term applied to a school of 19th- and 20th-century philosophers who, despite profound doctrinal differences, shared the belief that philosophical thinking begins with the human subject—not merely the thinking subject, but the acting, feeling, living human individual...

). Philosophical concepts for the process of education include Bildung and paideia
Paideia
In ancient Greek, the word n. paedeia or paideia [ to educate + - -IA suffix1] means child-rearing, education. It was a system of instruction in Classical Athens in which students were given a well-rounded cultural education. Subjects included rhetoric, grammar, mathematics, music, philosophy,...

.

Educational Psychology

Educational psychology
Educational psychology
Educational psychology is the study of how humans learn in educational settings, the effectiveness of educational interventions, the psychology of teaching, and the social psychology of schools as organizations. Educational psychology is concerned with how students learn and develop, often focusing...

 is an empirical science that provides descriptive theories of how people learn. Examples of theories of education in psychology are: constructivism
Constructivism (learning theory)
Constructivism is a theory of knowledge that argues that humans generate knowledge and meaning from an interaction between their experiences and their ideas. During infancy, it was an interaction between human experiences and their reflexes or behavior-patterns. Piaget called these systems of...

, behaviorism
Behaviorism
Behaviorism , also called the learning perspective , is a philosophy of psychology based on the proposition that all things that organisms do—including acting, thinking, and feeling—can and should be regarded as behaviors, and that psychological disorders are best treated by altering behavior...

, cognitivism
Cognitive psychology
Cognitive psychology is a subdiscipline of psychology exploring internal mental processes.It is the study of how people perceive, remember, think, speak, and solve problems.Cognitive psychology differs from previous psychological approaches in two key ways....

, and motivational theory

Sociology of education

The sociology of education
Sociology of education
The sociology of education is the study of how public institutions and individual experiences affect education and its outcomes. It is most concerned with the public schooling systems of modern industrial societies, including the expansion of higher, further, adult, and continuing...

 is the study of how public institution
Institution
An institution is any structure or mechanism of social order and cooperation governing the behavior of a set of individuals within a given human community...

s and individual experiences affect education
Education
Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...

 and its outcomes. It is most concerned with the public schooling systems of modern industrial societies, including the expansion of higher
Higher education
Higher, post-secondary, tertiary, or third level education refers to the stage of learning that occurs at universities, academies, colleges, seminaries, and institutes of technology...

, further
Further education
Further education is a term mainly used in connection with education in the United Kingdom and Ireland. It is post-compulsory education , that is distinct from the education offered in universities...

, adult
Adult education
Adult education is the practice of teaching and educating adults. Adult education takes place in the workplace, through 'extension' school or 'school of continuing education' . Other learning places include folk high schools, community colleges, and lifelong learning centers...

, and continuing
Continuing education
Continuing education is an all-encompassing term within a broad spectrum of post-secondary learning activities and programs. The term is used mainly in the United States and Canada...

 education. Examples of theories of education from sociology include: functionalism, conflict theory, social efficiency, and social mobility
Social mobility
Social mobility refers to the movement of people in a population from one social class or economic level to another. It typically refers to vertical mobility -- movement of individuals or groups up from one socio-economic level to another, often by changing jobs or marrying; but can also refer to...

.

Educational anthropology

Educational anthropology
Educational anthropology
Educational anthropology is a sub-field of anthropology and is widely associated with the pioneering work of George Spindler. As the name would suggest, the focus of educational anthropology is obviously on education, although an anthropological approach to education tends to focus on the...

 is a sub-field of anthropology
Anthropology
Anthropology is the study of humanity. It has origins in the humanities, the natural sciences, and the social sciences. The term "anthropology" is from the Greek anthrōpos , "man", understood to mean mankind or humanity, and -logia , "discourse" or "study", and was first used in 1501 by German...

 and is widely associated with the pioneering work of George Spindler
George Spindler
George Dearborn Spindler was a leading figure in 20th century anthropology and regarded as the founder of the anthropology of education. He edited a very large series of short monographs, turning nearly every significant ethnographic text of the 20th century into a shorter work accessible to the...

. As the name would suggest, the focus of educational anthropology is obviously on education, although an anthropological approach to education tends to focus on the cultural aspects of education, including informal as well as formal education. As education involves understandings of who we are, it is not surprising that the single most recognized dictum of educational anthropology is that the field is centrally concerned with cultural transmission.. Cultural transmission involves the transfer of a sense of identity between generations, sometimes known as enculturation
Enculturation
Enculturation is the process by which a person learns the requirements of the culture by which he or she is surrounded, and acquires values and behaviours that are appropriate or necessary in that culture. As part of this process, the influences which limit, direct, or shape the individual include...

 and also transfer of identity between cultures, sometimes known as acculturation
Acculturation
Acculturation explains the process of cultural and psychological change that results following meeting between cultures. The effects of acculturation can be seen at multiple levels in both interacting cultures. At the group level, acculturation often results in changes to culture, customs, and...

. Accordingly thus it is also not surprising that educational anthropology has become increasingly focussed on ethnic identity and ethnic change..

Organizational and leadership theory

  • Tracking
    Tracking (education)
    Tracking is separating pupils by academic ability into groups for all subjects or certain classes and curriculum within a school. It may be referred as streaming or phasing in certain schools. In a tracking system, the entire school population is assigned to classes according to whether the...


Educational theorists

  • Michael Apple
    Michael Apple
    Michael W. Apple is a leading critical educational theorist, recognized for numerous books and scholarly interests, which center on education and power, cultural politics, curriculum theory and research, critical teaching, and the development of democratic schools.He is currently the , at the...

  • William Chandler Bagley
  • Charles Beard
    Charles Beard (disambiguation)
    Charles Beard was a U.S. historian.Charles Beard may also refer to:* Charles Beard Izard , 19th century New Zealand MP* Edmund Charles Beard , British Major-General during the Second World War...

  • Allan Bloom
    Allan Bloom
    Allan David Bloom was an American philosopher, classicist, and academic. He studied under David Grene, Leo Strauss, Richard McKeon and Alexandre Kojève. He subsequently taught at Cornell University, the University of Toronto, Yale University, École Normale Supérieure of Paris, and the University...

  • Theodore Brameld
    Theodore Brameld
    Theodore Brameld was a leading philosopher and educator who supported the educational philosophy of social reconstructionism. His philosophy first originated in 1928 when he enrolled as a doctoral student at the University of Chicago in the field of philosophy where he trained under the...

  • Harry Broudy
    Harry Broudy
    Harry S. Broudy is a Polish-born educator.Broudy attended Massachusetts Institute of Technology, Boston University where he received his Bachelors Degree in German literature and philosophy in 1929. From there he went to Harvard University and earned his Masters degree in 1933 and his Ph.D in 1936...

  • Nicholas Burbules
    Nicholas Burbules
    Nicholas C. Burbules is a Gutgsell Endowed Professor of Education Policy, Organization and Leadership and an affiliate of the Unit for Criticism and Interpretative Theory at the University of Illinois at Urbana-Champaign...

  • George Counts
    George Counts
    George Sylvester Counts was an American educator and influential education theorist.An early proponent of the progressive education movement of John Dewey, Counts became its leading critic affiliated with the school of Social Reconstructionism in education. Counts is credited for influencing...

  • John Dewey
    John Dewey
    John Dewey was an American philosopher, psychologist and educational reformer whose ideas have been influential in education and social reform. Dewey was an important early developer of the philosophy of pragmatism and one of the founders of functional psychology...

  • Kieran Egan
  • Paulo Freire
    Paulo Freire
    Paulo Reglus Neves Freire was a Brazilian educator and influential theorist of critical pedagogy.-Biography:...

  • Howard Gardner
    Howard Gardner
    Howard Earl Gardner is an American developmental psychologist who is a professor of Cognition and Education at Harvard Graduate School of Education at Harvard University, Senior Director of Harvard Project Zero and author of over twenty books translated into thirty languages. Since 1995, he has...

  • Henry Giroux
    Henry Giroux
    Henry Giroux, born September 18, 1943, in Providence, Rhode Island, is an American cultural critic. One of the founding theorists of critical pedagogy in the United States, he is best known for his pioneering work in public pedagogy, cultural studies, youth studies, higher education, media studies,...

  • Daniel A. Greenberg
    Daniel Greenberg (educator)
    Daniel A. Greenberg , one of the founders of the Sudbury Valley School, has published several books on the Sudbury model of school organization, and has been described by Sudbury Valley School trustee Peter Grey as the "principal philosopher" among its founders...


  • John Caldwell Holt
    John Caldwell Holt
    John Caldwell Holt was an American author and educator, a proponent of homeschooling, and a pioneer in youth rights theory.-Biography:...

  • Bell Hooks
    Bell hooks
    Gloria Jean Watkins , better known by her pen name bell hooks, is an American author, feminist, and social activist....

  • Robert Hutchins
    Robert Hutchins
    Robert Maynard Hutchins , was an educational philosopher, dean of Yale Law School , and president and chancellor of the University of Chicago. He was the husband of novelist Maude Hutchins...

  • Ivan Illich
    Ivan Illich
    Ivan Illich was an Austrian philosopher, Roman Catholic priest, and "maverick social critic" of the institutions of contemporary western culture and their effects on the provenance and practice of education, medicine, work, energy use, transportation, and economic development.- Personal life...

  • Jonathan Kozol
    Jonathan Kozol
    Jonathan Kozol is a non-fiction writer, educator, and activist, best known for his books on public education in the United States. Kozol graduated from Noble and Greenough School in 1954, and Harvard University summa cum laude in 1958 with a degree in English Literature. He was awarded a Rhodes...

  • Peter McLaren
    Peter McLaren
    Peter McLaren is a Professor in the Division of Urban Schooling, the Graduate School of Education and Information Studies, University of California, Los Angeles . He is the author and editor of forty-five books and hundreds of scholarly articles and chapters...

  • Richard Mitchell
  • Maria Montessori
    Maria Montessori
    Maria Montessori was an Italian physician and educator, a noted humanitarian and devout Catholic best known for the philosophy of education which bears her name...

  • A.S. Neill
  • Michael Adrian Peters
    Michael Adrian Peters
    Michael Peters is a Professor in Educational Policy, Organization, and Leadership at the University of Illinois at Urbana–Champaign, Editor of Educational Philosophy and Theory, and a lifelong Fellow of the New Zealand Academy of Humanities.-Education:...

  • Harold Rugg
    Harold Rugg
    Harold Rugg was an educational reformer in the early to mid 1900s, associated with the Progressive Education Movement. Originally trained in civil engineering at Dartmouth College , Rugg went on to study psychology, sociology and education at the University of Illinois where he completed a...

  • Rudolf Steiner
    Rudolf Steiner
    Rudolf Joseph Lorenz Steiner was an Austrian philosopher, social reformer, architect, and esotericist. He gained initial recognition as a literary critic and cultural philosopher...

  • Max Stirner
    Max Stirner
    Johann Kaspar Schmidt , better known as Max Stirner , was a German philosopher, who ranks as one of the literary fathers of nihilism, existentialism, post-modernism and anarchism, especially of individualist anarchism...



See also

  • Anti-schooling activism
  • Classical education movement
    Classical education movement
    The Classical education movement advocates a form of education based in the traditions of Western culture, with a particular focus on education as understood and taught in the Middle Ages. The curricula and pedagogy of classical education was first developed during the Middle Ages by Martianus...

  • Humanistic education
  • International education
    International education
    International education can mean many different things and its definition is debated. Some have defined two general meanings according to its involvement of students...

  • Peace education
    Peace education
    Peace education may be defined as the process of acquiring the values, the knowledge and developing the attitudes, skills, and behaviors to live in harmony with oneself, with others, and with the natural environment....


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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