System, Processes, and Interactions


A system is any region in space or quantity of matter set aside for analysis. Everything not inside the system is in the surroundings. The system boundary is an infinitesimally thin surface, real or imagined, that separates the system from its surroundings.

Systems may be classified according to whether they exchange mass with the surroundings. A closed system is a system that does not exchange mass with its surroundings; thus, it has a fixed and unchanging mass although its volume may change. An open system is a system that may exchange mass with its surroundings; thus, its mass and volume may change.

Processes and Interactions

Systems change state by interacting with their surroundings. A process is the means by which a system changes state. An interaction between a system and its surroundings occurs when an extensive property crosses the system boundary.


References for Further Information

  1. Gagne, R .M., L.J. Bridges, and W. W. Wagne. 1998. Principles of Instructional Design. Orlando, FL: Holt, Rinehart and Winston, Inc.
  2. Hanson, G., and B. Price. 1992. Academic Program Review. In: M. A. Wjitley, J. D. Porter, and R. H. Fenske (eds.). The Primer for Institutional Research. Tallahassee: Association for Institutional Research.
  3. Satterly, D. 1989. Assessment in schools. Oxford, UK: Basil Blackwell Ltd.