Twenty Questions Tree Ask yes or no. Sort the world. Then meet the objects your tree never saw.

1. Quick start — read this, start playing

   • Lay out the 16 Training cards. Keep the 6 Surprise cards folded and face-down.
   • On your Tree Mat, write a question number in the top box. Every card that answers YES goes left, NO goes right. Each card prints its own answers.
   • Keep asking until every pile holds only one kind. Then write that kind (Animal, Plant, Machine or Thing) in the box at the end of the branch.
   • Perfect tree? Score 8 minus the questions you used. Then run each Surprise through and unfold it to check: +2 for each one your tree gets right.
   • That's the whole game. Everything below is for when a question comes up.

2. Setup

   • Cut out the 22 Object cards. 16 are Training cards with their kind printed on them. 6 are Surprise cards: fold each on the dotted line so the answer is hidden, and set them aside face-down.
   • Play solo, or split into two teams. Each team takes a Tree Mat and a pencil.
   • The 8 questions are printed on the Tree Mat. Every Object card shows its own YES / NO answer to each one, by number.

3. Build your tree

   • Pick a question and write its number in the top box. Split the Training cards: YES answers into a pile on the left, NO on the right.
   • Look at each pile. All one kind? Write that kind in the next box down, and that branch is done. Mixed? Write another question number and split that pile again.
   • A branch can ask at most 3 questions, the height of the mat. You can use a question more than once in different branches.
   • Check it: send every Training card down your tree from the top. Each one must land on its own kind. If one doesn't, fix the tree before you score.

4. Test it on Surprises

   • Take the Surprise cards. For each one, start at the top of your tree and follow its answers down to a kind. Say it out loud.
   • Unfold the card to check. Right? Your team scores the points.
   • With two teams, run every Surprise through both trees. Different trees can disagree.

5. How to score

   • Perfect tree: 8 minus the number of questions on it (at least 1). A tree with 4 questions scores 4.
   • Each Surprise your tree sorts right: +2.
   • Most points wins. Ties share the win.

6. What the tree teaches

   • Features: a computer can't see a dog. It sees answers to questions: alive? makes sounds? Those answers are called features.
   • Decision tree: yes/no questions in a row. Real AI systems sort email, photos and loan forms this way, just with thousands of questions.
   • Smaller isn't always smarter: the smallest perfect tree uses 3 questions, and every one of those trees gets at least one Surprise wrong.
   • Training vs. testing: a tree is only as good as the objects it learned from. Coral and robot dogs weren't in the training pile.
   • Edge cases: is a Venus flytrap moving? Is a wind-up car a machine? Real AI meets these all the time, and people have to decide.

7. Variants

   • Smallest tree race: who can find a perfect tree with the fewest questions? (It can be done with 3.)
   • Add your own: write a new Object card for something in the room, answers and all. Does your tree sort it right?
   • Retrain: after the Surprises, add them to the Training pile and build again. Does the tree change?

Downloads

• Instruction sheet

  Plain paper · 1 page · 8.5 × 11

  One 8.5 × 11 page for the table — quick start, setup, turns, and scoring.

  Open Download

• Full rules

  Plain paper · duplex · 2 pages

  Same game, longer type — plus what the cards teach and the variants.

  Open Download

• Object cards

  Plain paper · 2 pages · scissors

  22 cut-out cards, each printing its own yes/no answers. The Surprise cards fold to hide the answer.

  Open Download

• Tree Mat

  Plain paper · 1 page · landscape

  The questions, and an empty tree to fill in with question numbers and kinds. One per team.

  Open Download