Ecological systems theory: This theory looks at a child's development within the context of the system of relationships that form his or her environment. Bronfenbrenner's theory defines complex "layers" of environment, each having an effect on a child's development. This theory has recently been renamed "bioecological systems theory" to emphasize that a child's own biology is a primary environment fueling her development. The interaction between factors in the child's maturing biology, his immediate family/community environment, and the societal landscape fuels and steers his development. Changes or conflict in any one layer will ripple throughout other layers. To study a child's development then, we must look not only at the child and her immediate environment, but also at the interaction of the larger environment as well. The various terms in this graphic are links that lead to pages explaining their implications in this theory. The microsystem – this is the layer closest to the child and contains the structures with which the child has direct contact. The microsystem encompasses the relationships and interactions a child has with her immediate surroundings (Berk, 2000). Structures in the microsystem include family, school, neighborhood, or childcare environments. At this level, relationships have impact in two directions -both away from the child and toward the child. For example, a child's parents may affect his beliefs and behavior; however, the child also affects the behavior and beliefs of the parent. Bronfenbrenner calls these bi-directional influences, and he shows how they occur among all levels of environment. The interaction of structures within a layer and interactions of structures between layers is key to this theory. At the microsystem level, bi-directional influences are strongest and have the greatest impact on the child. However, interactions at outer levels can still impact the inner structures. The mesosystem – this layer provides the connection between the structures of the child's microsystem (Berk, 2000). Examples: the connection between the child's teacher and his parents, between his church and his neighborhood, etc.