Guess My Rule

Why it works

Many systems that make decisions about people will not say how they decide. The only way to understand them is to try things and watch what happens. That is exactly what your child does here. They also run into a deep idea on their own: a guess can fit every example so far and still be wrong.

How to play

1. Secretly choose a rule, such as “made of metal,” “smaller than my hand,” or “something you could put in water.”
2. Place three objects in “yes” and three in “no” to get started.
3. Your child picks a new object and asks, “Yes or no?” You place it. They keep testing.
4. When they think they know the rule, they say it out loud. If it is not quite right, keep going.
5. Swap roles. Now you are the detective.

Make it easier, make it harder

• Easier: use rules about colour or size, and start with more examples.
• Harder: use a rule with two parts (“metal and smaller than my hand”), or a rule that fits the first examples by coincidence.

Talk about it

• Which test told you the most? Why that one?
• Did you ever think you had it, and then find out you didn’t?
• If a machine said “no” to you and would not explain why, how could you find out its rule?

If your child asks

“Why wouldn’t a machine just tell you its rule?” Sometimes the company that made it keeps the rule secret. Sometimes the rule is so complicated, learned from millions of examples, that even the people who built it cannot say it in one sentence. People are still arguing about how much a machine should have to explain when it decides something about you.