This is the final exam for Feedback Loops & Systems Thinking. It pulls together the whole course: stocks and the flows that fill and drain them, reinforcing loops that make “more beget more,” balancing loops that hunt a goal and resist change, the delays that turn those balancers into oscillators, and the leverage points where a small push can move a whole system. Several questions look easy until you notice that a stock is masquerading as a flow, or a reinforcing loop is wearing a balancing disguise. Reason each one through.
How this exam works
Read carefully — this exam is final. Each question appears one at a time. Once you submit an answer it is locked for good: there’s no going back, no retry, and no restart. Your score is hidden until the end, where you’ll see a pass/fail verdict. The pass mark is 70%. A few questions ask you to select all correct answers.
What is the cleanest distinction between a stock and a flow?
Select an answer to continue.
Course Recap
Big picture
Feedback loops & systems thinking, in one picture
- Feedback Loops & Systems Thinking
- Stocks & flows
- Stock = accumulated level; flow = the rate that fills/drains it. Never confuse CO2 (stock) with emissions (flow). Stocks create inertia.
- Reinforcing loops
- "More begets more" — exponential growth/collapse; virtuous & vicious share one structure; always hits a limit eventually.
- Balancing loops
- Sense the gap to a goal and shrink it — "more leads to less"; thermostats, homeostasis; they resist change (policy resistance).
- Delays & oscillation
- A balancing loop + delay overshoots and oscillates (acting on stale data) — the scalding shower, the bullwhip. Fix: shorten the delay or ease off.
- Leverage points
- Numbers → buffers → loop structure → information → rules/incentives → goals & paradigms. The obvious lever is the weak one.
- Stocks & flows
Key takeaways
Systems thinking is the habit of seeing the loops beneath the events. Start by separating stocks (accumulated levels) from the flows that fill and drain them — confusing the two is the cardinal error (emissions can fall while CO2 still rises). Learn the two engines: reinforcing loops that make more beget more (compounding, bubbles, bank runs — always racing toward a limit), and balancing loops that hunt a goal and resist change (thermostats, homeostasis, policy resistance). Add a delay to a balancing loop and it stops gliding and starts oscillating — the scalding shower, the supply-chain bullwhip — so the fix is to shorten the delay or ease off the correction rather than chase stale data. And when you want to change a system, climb the leverage ladder: numbers and buffers are weak; rules, incentives, goals, and paradigms are strong. Above all, beat the recurring pitfall — linear thinking — which blinds you to both exponential growth and delayed oscillation. Stop fighting the symptoms; find the loop.