Diagrams of systems reveal different views of their behavior.

Stock-and-flow diagrams show stocks, flows, and feedback loops. Thick arrows with faucets indicate flows, clouds indicate outside sources and destinations of flows, feedback loops are usually thin arrows interacting with flows or other feedback loops, and feedback loops indicate their type with a B or R label.

Behavior over time graphs show a stock’s volume and changes over time.rM3

  1. Donella H. Meadows and Diana Wright, Thinking in Systems: A Primer (White River Junction, Vt: Chelsea Green Pub, 2008). (See notes.)