Buy or sell baskets of apples against 10 computer buyers and 10 computer sellers. Each round changes something in the market. Predict what happens to the price, send your order, and watch where the market clears.
$10.00
Blue steps: buyer bids from highest to lowest. Gold steps: seller asks from lowest to highest. Your order is the thick green step. Across the bottom: number of baskets.
Every round you are either a buyer or a seller. A buyer gets a private value, the most a basket of apples is worth to them. A seller gets a private cost, the least they can accept. You send one order: a bid if you are buying, an ask if you are selling. The 20 computer traders do the same. The game then lines up all bids from high to low and all asks from low to high, finds the largest number of trades where each bid is at least the matching ask, and sets one price that clears the market.
Your profit is your value minus the price when you buy, or the price minus your cost when you sell. Before most rounds you also predict what the change in the market will do, and a correct prediction is worth 2 points.
In the game, when demand rises, both the price and the number of baskets sold go up. When supply falls, the price goes up but fewer baskets change hands. With a cap below the market price, more buyers want apples than sellers will sell, which is a shortage. With a floor above it, sellers are left with apples nobody buys, which is a surplus. In both of those rounds some willing traders miss out, and the game picks who trades at random.
Watch your own order too. Bidding more than your value can make you buy at a loss, and asking less than your cost can make you sell at a loss. Bidding below your value rarely moves the price in a market with 20 other traders, but it can make you miss a profitable trade.
This game follows the design of the market experiments run by economist Vernon Smith. The Nobel Prize summary of his work describes subjects who were randomly given roles as buyers and sellers with different valuations. In results he published as early as 1962, the prices they reached were very close to the theoretical equilibrium, even though no one had the information needed to calculate it. Smith shared the 2002 Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for establishing laboratory experiments as a tool in economic analysis.
Stock trading runs on the same idea: the SEC notes that electronic networks automatically match buy and sell orders at specified prices. See how the stock market works and bid-ask spread explained, or try quoting both sides yourself in the market-making drill.
Classroom game, not financial advice. The apples, values and costs are made up and there is no real money.
It fits middle school economics through college principles courses. Younger students can play for the story in each round, while older students can sketch the curves and check the equilibrium price after each result.
The game sorts bids from highest to lowest and asks from lowest to highest, finds the most trades where each bid is at least the matching ask, and picks the middle of the price range that clears the market. Everyone who trades pays or receives that one price.
Only if your order crosses your own value or cost. A buyer who bids above their value can end up paying more than the apples are worth to them, and a seller who asks below their cost can sell at a loss.
Yes. It needs no account and runs in a browser on laptops or phones. A full game of 8 rounds takes about 10 minutes, and the price cap and price floor rounds make good discussion starters.