Young Scientists
Twenty Doors
A creature hides behind twenty doors. Corner it with yes/no questions — backbone? warm-blooded? can it fly? — and each answer crosses out every creature that doesn't match. Name it in as FEW questions as possible. Solo against par, and live whole-class races. Behind the fun: a real classification key, and the reason no strategy on Earth can beat a certain number of questions.
For Educators
Built for the classroom
Information theory through play — and biological classification. A yes/no answer carries at most ONE BIT, so the best question splits the survivors closest to 50/50; students SEE this because every question shows its live ✓/✗ split, and a longshot ("is it a tiger?") barely narrows the field while "does it have a backbone?" halves it. The deep result, in the gated theorem: it takes at least ceil(log2 N) questions to single out one of N creatures — no cleverness beats that floor, and splitting in half every time is how you reach it. A biologist's dichotomous key IS exactly this binary search over life. The game shows the live ✓/✗ DATA but never flags the "best" question — students discover the even-split idea by TRYING, not by being told; question-budget difficulty tiers then force them to plan before they ask. Our test proves every creature has a distinct trait vector and that the greedy 50/50 splitter corners each one in near-optimal questions, every run.
Grades 4+ · 31 well-known creatures × 16 yes/no traits · par is 5 questions (ceil(log2 31)); solo earns the Sleuth License by naming the creature in 6 or fewer · solo difficulty sets a QUESTION BUDGET (Explorer 8 / Detective 6 / Mastermind 5) · live races 3/5/10 minutes, with an optional question budget.
Three ways to play
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Play solo
A hidden creature; ask yes/no questions and watch the ✓/✗ splits — no question is ever marked "best", you discover that by trying. Three difficulty tiers set a question BUDGET (Explorer 8 / Detective 6 / Mastermind 5): run out without naming and you lose, so spend each question where it rules out the most. Name it in 6 or fewer to earn the Sleuth License.
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Host a Race
One hidden creature for the whole room on the projector; pick 3/5/10 minutes and, optionally, a question budget (5–8) so students must think before they ask. Students race to name it in the fewest questions; the server holds the secret.
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Join on any device
Ask yes/no questions, cross out creatures, and name your guess. Fewest questions wins — a wrong name costs a question.
Run a live class in 5 steps
- Open the Race — pick the length; share the 4-letter code / QR / link.
- Students join on any device; one hidden creature is the same for everyone.
- They ask yes/no questions (the server answers from the secret) and narrow on their own screen.
- First to NAME it with the fewest questions tops the ladder; a wrong name costs a question.
- At the end the creature is revealed. Ask the room: which question halved the field fastest, and why?
Tip: host on a laptop or projector (the big screen shows the code, QR and leaderboard); students join on their phones or laptops.
