Model an environmental system using stocks, flows, and feedback loops, and distinguish negative (stabilizing) feedback from positive (amplifying) feedback.
A system is a set of connected parts that influence each other -- a pond, a forest, a city's water supply, even the whole planet. Every system has stocks (amounts stored somewhere, like water in a lake) and flows (movement in or out, like rainfall in and evaporation out). Environmental problems are rarely a straight line from one cause to one effect; they are usually loops.
A feedback loop occurs when a change in a system eventually loops back to affect itself. Negative feedback is stabilizing: a change triggers a response that pushes the system back toward where it started, the way a thermostat turns the heat off once a room is warm enough. Positive feedback is amplifying: a change triggers a response that pushes the system further in the same direction, like a small campfire spreading to dry brush, which burns hotter, which ignites more brush. "Positive" here does not mean "good" -- it means the effect reinforces itself.
Mastery looks like: They can label stocks, flows, and at least one feedback loop in a described system, and correctly classify a feedback loop as amplifying or stabilizing with a stated reason.
Common stumbles: Assuming all feedback loops are harmful; describing a one-directional cause and effect and calling it a "loop" without an actual return path back to the start.