# Lemonade Stand Game for the Classroom — Price, Weather, Profit Source: https://decka.dev/classroom/economics/lemonade-stand-game Students run lemonade stands in pairs through ten days of summer, one ticket a stand each day. Every stand's day lands on the big screen as a cup, price across and profit up, so the room draws the profit hill that no one stand could see. ## What it teaches Students find the most profitable price from their own room's results: each stand's day is a point of price against profit, and together they draw a hill whose top no single stand could find alone. They see why the dearest cup does not earn the most, weigh selling out against pouring cups away, and use break-even to decide when a stand should stay shut. ## Run the lemonade stand game with the whole class The lemonade stand game asks one question a day: what should a cup cost? Here every stand in the room plays the same summer at once, a pair sending one ticket between them; in an odd class, one student runs a stand alone. Each stand has its own street, so no stand takes another's customers: a price is a decision about the town, not a fight with the stand next door. The ten days run in three acts. For the first three, a stand sets only its price, and Grandma makes as many cups as people want at 20p each; the stall costs £5 for the day. From day four the stand also decides how many cups to make: unsold cups are poured away, and a stand that makes none stays shut and pays no stall fee. For the last three days it may put up a £10 sign that brings more people past. Each day's weather opens with the day, and any member of a stand can change its ticket until the stalls close. Press “Close the stalls”, or let the day's clock run out, and every stand's day lands on the big screen as a cup: its price across, its profit up. Each cup walks from where its stand's cup stood the day before, stands that chose alike share one cup and its count, and the model's line shows the most a stand could make at each price. Then “Next day” opens the next one. After ten days the screen sets out every stand's cash, split by the rainy day's one choice, and whether each sign paid for itself. The big screen never names a stand: each cup and each stand's closing cash is anonymous. Each phone shows only its own stand's ticket, its day, its cash and its place. The summer's weather is written before class, the same for every stand, and the brief and the results say so. Try the screen-and-phone preview: the phone is yours, at Stand 7 beside a practice teammate, and fourteen practice stands send their tickets through the same runtime as the lesson. A note for the teacher, with the numbers the room is never shown. A day's customers are its crowd, less a number for every pound on the price, plus a sign's draw where a sign is offered. A hot day brings 150 and loses 80 a pound: best £1.06 a cup, for £51.76, and with its sign of 25 people, £1.21, for £64.79. A cloudy day brings 70 and loses 70: best 61p, for £6.48, where its sign of 10 people costs more than it brings in. A warm day brings 110 and loses 80: best 81p, for £23.06. A rainy day brings 30 and loses 50: even its best price, 41p, loses £2.90 once the stall is paid, so the best a stand can do is stay shut. A heatwave brings 190 and loses 80: best £1.31, for £90.46, and with its sign of 30 people, £1.46, for £116.04. Each weather's numbers, and each act's clock, are yours to change before you run it. ## Classroom debrief On day one, how far apart were the room's prices? Where had the room got to by day three, and what made you move? Why didn't the most expensive stand make the most money? What happens to the hill if you double the price? On the rainy day, who opened, who stayed shut, and who was right? What does break even mean for that choice? Your stand sold out on a hot day. Was that good news? What would one more cup have earned, and what does a wasted cup cost? When did the sign pay for itself, and when didn't it? Why? ## Lemonade stand game questions, answered ### What do I need besides phones? Nothing to print. Every student joins on their own phone and is dealt into a stand of two, or in an odd class one student runs a stand alone, and each stand shares one ticket: any member can send it or change it until the stalls close. ### Do the stands compete for the same customers? No. Each stand has its own street, so one stand's price never takes another's customers. Every stand faces the same town on the same day, which is what lets the room's cups draw one profit hill. ### Where does the weather come from? The summer is written before class, the same for every stand, and each day's weather is released only as that day opens, so no stand knows tomorrow's. The brief and the results show a line that says so, with the summer's short fingerprint. ### Are stands named or ranked on the projector? No. The big screen shows each stand's day as an anonymous cup and its cash after ten days as an anonymous notch, never a stand's name or number. Each phone shows only its own stand's ticket, day, cash and place. ### What if a stand sends no ticket? Its stand stays shut that day and pays no stall fee, so its cash does not move, and its phone says so. On a day when stands choose whether to open, the screen counts it apart from the stands that chose to stay shut. ### Can I change the weather or the clocks? Yes. Before you run it, each weather's crowd, how many it loses for every pound on the price and how many a sign draws are yours to set, as are each act's day clock (ninety seconds, then two minutes, by default), the sizes of the stands and every word on the screen and the phones. ### How long does it take? Allow about thirty minutes: a minute or two for the brief, ten days on their clocks with a short reveal after each, and the season's results and the debrief. You can close the stalls as soon as every ticket is in. ## Run the lesson Present the boards in PowerPoint and Decka. Students scan a QR code or open the session link to join from their phone browsers.