Mind Games

Auction Lab

Grades 6+ · whole-class + solo

Sealed-bid auctions with play coins — and a Nobel-prize idea hiding in round one. In the Card Shop every kid gets a SECRET value for the item; highest bid wins but pays the SECOND-highest. Discover the bidding habit that is mathematically unbeatable, then meet its evil twin: the Money Pit, where the top TWO bidders both pay and smart people overpay on purpose. Solo Auction House + live class rooms.

For Educators

Built for the classroom

Auction theory as a hands-on lab. The Card Shop is a Vickrey (second-price) auction: students discover that bidding your TRUE value can never be beaten — the Dojo's Time Machine lets them replay a round with every possible bid and SEE that the price is set by someone else's bid (Vickrey 1961, Nobel 1996; eBay's proxy bidding works exactly this way). Pay-What-You-Bid flips it: now shading below value is right and there is no single best answer. The Money Pit (Shubik's dollar auction) teaches sunk cost viscerally — the top two pay, and the projector shows the room paying MORE than the prize is worth. Coins can go negative; the winner's curse gets its own moment.

Grades 6+ · formats: Card Shop (second-price), Pay-What-You-Bid (first-price), the Money Pit (top-two-pay), or Lab Mix (rotates) · 3/5/7 rounds · bids 0–150, secret values 40–100.

Three ways to play

Auction House (solo)

Six auctions against four rival bidders with tell-tale habits — honest Abe, shading Sly, chaotic Wobble, escalating Vex. Solo unseals their bids AND values after each round. End a campaign +25 coins up to earn the license.
Host a Room

Open a room on the projector; a 4-letter code + QR + join link appear. Pick the auction format; every reveal shows the anonymous bid bars and what the winner actually PAID.
Join on any device

Students get their secret value, bid 0–150 in private, and can change it until the reveal. Values and coins stay private; only winners are named.

Run a live class in 5 steps

Open the Room — pick the format (start with the Card Shop) and the number of rounds.
Share the 4-letter code / QR / link; students join on any device and each receives a SECRET value.
Each round: sealed bids tick in as name-flags; the reveal shows the bid bars, the winner, and the price — set by the SECOND bid.
After round 3, ask: has anyone found a bid you never regret? Don't confirm — let the Time Machine in the Dojo do it.
Run the Money Pit last. Add up what the room paid against the 100-coin prize. Ask who "won."

Tip: host on a laptop or projector (the big screen shows the code, QR and leaderboard); students join on their phones or laptops.