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Spark & Whetstonethe grown-up commons

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Thinking in Loops

Four short lessons on how things build up and run down: stocks and flows, loops that snowball or settle, why delays make us overshoot, and why every model is an argument.

For grown-ups, from what NexusForge teaches children at Spark & Anvil.

  1. Lesson 1Stocks and flows
  2. Lesson 2Loops that snowball or settle
  3. Lesson 3Delays
  4. Lesson 4Every model is an argument
At the table · 4 (or 2 people taking two seats each)

The lemonade line

You'll need: paper slips, a pencil each, and coins or buttons for crates.

  1. Sit in a row: the stand, the shop, the warehouse and the farm. Each seat starts with 12 crates.
  2. Each turn the stand draws a customer card and sells that many cups. Every seat ships what it is asked for, if it has it.
  3. Each seat writes an order on a slip and passes it up the line. Slips and crates both take two turns to arrive.
  4. After a few turns the stand's customers go from 4 to 8 a turn and stay there. Keep playing for twenty turns.
  5. Lay out every seat's orders in a row and compare. Talk about why the farm's swings were so much bigger than the stand's.

Open The lemonade line: run it, or print the seat sheets →

Print the guidebook (all lessons + the table activity) →