people that live in the area. Human-environment interaction This theme describes how people interact with the environment, and how the environment responds, with three key concepts: Dependency: Humans depend on the environment. Adaptation: Humans adapt to the environment. Modification: Humans modify the environment. Sub-themes include "the earth as an environmental system" (including the role and problems of technology, environmental hazards and limits, and adaptation) and "ethics and values" (differing cultural values and the trade-off between economic development and environmental protection). In the original 1984 Guidelines for Geographic Education: Elementary and Secondary Schools, this was called “relationships within places". It focused on the advantages and disadvantages for human settlement in places. It was later renamed to human-environment interaction. This theme is not exclusive to geography, as it is a goal for many disciplines of study. Movement Movement is the travel of people, goods, and ideas from one location to another. Examples of movement include the United States' westward expansion, the Information Revolution, and immigration. New devices such as the airplane and the Internet allow physical and ideological goods to be transferred long distances in short time intervals. A person's travel from place to place, and the actions they perform there are also considered movement. Places are connected by movement: Methods of transportation (transportation geography) – public transportation, private transportation, freight transportation Movement in everyday life History of movement Economic factors influencing movement Energy or mass induced movement – the water cycle, tectonic plates, movements within ecosystems, etc. Global interdependence Models of human interaction, including gravity models and central place theory In the original 1984 Guidelines for Geographic Education: Elementary and Secondary Schools document, movement was called “relationships between places". Transportation routes and telephone lines that link people all over the world are visible examples of relationships between places. Region Regions are areas with distinctive characteristics: human characteristics, such as demographics or politics, and physical characteristics, such as climate and vegetation. For example, the US is a political region because it shares one governmental system. Regions may have clear, well-defined borders or vague boundaries. Uniform region – "defined by some uniform cultural or physical characteristic", such as the Bible Belt or New England Functional region – space organized around a focal point, such as a metropolitan area or around the flow of something, like the water of the Amazon Basin, or the flow of travelers in an airport Cultural diversity – regions