What theory describes how a change in one element affects all other elements in a system?

The answer is Systems Theory, which focuses on understanding how various components of a system interact with one another. In this context, the theory posits that all elements within a system are interconnected, meaning that any change in one part can lead to changes in others. This perspective is particularly useful in fields like social work, where individual behavior cannot be fully understood without considering the larger social environment and the myriad influences at play.

For example, in a school setting, a student's academic performance may be impacted not only by their personal characteristics (like motivation or ability) but also by family dynamics, peer relationships, and school policies. Systems Theory encourages practitioners to take a holistic view by recognizing that individuals exist within complex social systems.

Other options, while important in their own rights, do not specifically address the interconnectivity of elements within a system. The Ecological Perspective emphasizes the interactions between individuals and their environments but does not encapsulate the broader idea of system interdependencies as effectively as Systems Theory. Behavioral and Cognitive Theories primarily focus on individual behavior and thought processes without emphasizing the systemic influences.