Guess, then check: a 20-minute AI activity for ages 8 to 10
Guess, then check is a printable 20-minute activity that shows children aged 8 to 10 how a machine learns a rule from examples. Your child sorts six example cards, writes a rule, tests it on new cards, changes one thing and tests again. You need paper, a pencil and 12 picture cards printed from this page.
Last reviewed: 20 October 2026 9 min read
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Print the cards and worksheet (PDF)
What does this activity teach about AI?
It teaches the core idea of machine learning: a rule learned from examples has to be tested on examples it has never seen. In this activity your child plays the machine. You play the person who labeled the examples.
The six example cards are labeled YES or NO. Your child looks for the rule that explains the labels, writes it down and uses it to predict new cards. Then you reveal the real answers. If the rule fails, the examples were hiding something, and your child fixes the rule and tests again.
What do you need?
- The 12 picture cards, printed from this page and cut out (black and white is fine: every card has its color written on it)
- The one-page worksheet (or any sheet of paper)
- A pencil
- Two pieces of paper labeled YES and NO to make two trays
- 20 minutes, with an adult nearby for the reveals
Keep the answer key (page 3) with the adult. Your child should not see it until the end.
How do you run Guess, then check?
Run it in five steps, about 20 minutes in all. Each step asks your child to commit to an answer before you reveal anything.
- Step 1. Sort the examples (4 minutes). Give your child cards 1 to 6. Each one is marked YES or NO in its corner. Ask them to put each card in the YES or NO tray and look at both piles. “What do the YES cards have in common? What do the NO cards have in common?”
- Step 2. Write a rule (3 minutes). Your child finishes the sentence on the worksheet: “A sticker goes in YES when …”. The rule must use one thing they can see on the card: its shape, its color, its size or its pattern. Do not say whether the rule is right.
- Step 3. Test on new cards (4 minutes). Give your child cards 7 to 10, one at a time, with no label. For each card, your child uses their rule to predict YES or NO and writes the prediction on the worksheet. Only then do you read the real answer from the answer key. Your child ticks or crosses each prediction.
- Step 4. Change one thing (4 minutes). Look at the crosses together. “Which cards did the rule get wrong? What do those cards have that the examples didn’t?” Your child changes one thing: the single detail the rule looks at. They write the new rule on the worksheet.
- Step 5. Test again (3 minutes). Give your child cards 11 and 12, which nobody has seen yet. Your child predicts with the new rule, then you reveal the answers. Finish with one question: “What made your first rule go wrong?” (2 minutes)
What does a wrong guess teach?
A wrong guess shows which detail the rule was really using. In the six example cards, every YES sticker is a red circle and every NO sticker is a blue square or triangle. Two rules fit the examples equally well: “red stickers go in YES” and “circles go in YES”.
Most children notice the color first. On cards 7 to 10, the color rule gets every card wrong: a blue circle is a YES, and a red square is a NO. The circle rule gets every card right. Nothing was wrong with your child’s thinking. The examples simply could not tell the two rules apart, and only new cards could.
Machines that learn from examples have the same problem. If every example of one answer happens to share an extra detail, a machine can learn that detail instead of the one that matters. That is why a learned rule is tested on cases it has never seen, and why a wrong answer on a fresh case is useful information, not a failure.
How should an adult help?
Help by asking, not telling. Read the instructions aloud if that helps, then let your child explain their idea before you offer yours.
- Keep the first rule as written. Do not let your child rub it out after the reveal. The first rule and its crosses are the most useful part of the worksheet.
- Ask for evidence. “Which card made you think that?” works better than “Are you sure?”
- “I can’t tell yet” is a good answer. If two rules both fit, say so. That is the point of Step 3.
- If your child guesses “circles” straight away, go straight to Step 3 anyway, then ask: “Could someone else have guessed a different rule from the same six cards?” Then try the older-children variation below.
- Keep the tone light. The rule was wrong, not the child.
How do you adapt it for older children?
For ages 11 to 18, hide a rule that uses two details at once (for example, “big AND circle”), or give details points and set a threshold (circle = 2, big = 1, spots = 1, YES at 3 or more), relabel cards 1 to 6 to match, then ask your child to count right and wrong predictions across every test card, keep every error in a table, and decide which mistake would matter more if YES meant “safe to eat”.
What does this activity not show?
It shows how a rule learned from a few examples can fit them and still fail on new cases. It does not show how real systems learn from very large numbers of examples, or how they store what they learn as numbers rather than a written sentence. In this activity a person keeps the true rule; a real machine has no answer key to check against unless people build and test one.
Where does Mechna Academy use the same idea?
Mechna Academy is a city of machines for curious children aged 8 to 18, opening first to ages 8 to 10. In each mission, a child guesses how a machine decides, then opens its Peek Hatch to check, changes one thing and tests it on a case it has never seen. Children learn how AI works this way, and they never chat with an AI.
Page 1: picture cards
Page 2: worksheet
GUESS, THEN CHECK Name or nickname: ____________ You are the machine. Six example cards are labeled YES or NO. Find the rule, then test it on cards you have never seen. STEP 1 SORT THE EXAMPLES Put cards 1 to 6 in the YES tray or the NO tray. The YES cards all have: ____________________________________________ The NO cards all have: ____________________________________________ STEP 2 WRITE A RULE My rule: A sticker goes in YES when ____________________________________ (Use one thing you can see: shape, color, size or pattern.) STEP 3 TEST ON NEW CARDS Guess first. Then your grown-up reads the real answer. Card My guess (YES / NO) Real answer Right? (✓ or ✗) 7 ________ ________ ____ 8 ________ ________ ____ 9 ________ ________ ____ 10 ________ ________ ____ My rule got ____ right and ____ wrong. STEP 4 CHANGE ONE THING The cards my rule got wrong were: ______________________________________ They had something the examples did not: _______________________________ My new rule: A sticker goes in YES when ________________________________ STEP 5 TEST AGAIN Card My guess (YES / NO) Real answer Right? (✓ or ✗) 11 ________ ________ ____ 12 ________ ________ ____ THINK ABOUT IT What made my first rule go wrong? _______________________________________________________________________ _______________________________________________________________________ Keep your first rule. Wrong guesses are how you found the real one.
Page 3: adult answer key (keep this page away from your child)
ANSWER KEY: GUESS, THEN CHECK
The hidden rule: CIRCLES go in YES. Everything else goes in NO.
Why it is tricky: in the examples (cards 1 to 6), every YES card is a red
circle and every NO card is blue. So "red goes in YES" fits the examples
just as well as "circles go in YES". Only the test cards can tell them apart.
Card Real answer "Red" rule says "Circle" rule says
7 YES NO (wrong) YES
8 NO YES (wrong) NO
9 YES NO (wrong) YES
10 NO YES (wrong) NO
11 YES NO (wrong) YES
12 NO YES (wrong) NO
If your child wrote "red AND circle": cards 7, 9 and 11 come out wrong.
If your child wrote a rule about size or spots: it will not fit cards 1 to 6;
ask them to check the examples again before Step 3.
Questions to ask:
- Which card made you think that?
- Could someone else guess a different rule from the same six cards?
- What made your first rule go wrong?
Older children (11 to 18): two harder hidden rules to try.
Label cards 1 to 6 with the new rule's answers before you start.
Rule A, "big AND circle":
YES = cards 1, 3, 9. NO = 2, 4, 5, 6, 7, 8, 10, 11, 12.
Rule B, points (circle = 2, big = 1, spots = 1, YES at 3 or more):
YES = cards 1, 3, 9, 11. NO = 2, 4, 5, 6, 7, 8, 10, 12.
(Card 2 scores 2 and card 8 scores 2: both just miss.)
Keep a table of every right and wrong prediction, and ask which wrong
answer would matter more if YES meant "safe to eat".Questions
It is written for children aged 8 to 10 and takes about 20 minutes with an adult nearby. Children aged 11 to 18 can play the variation, which hides a two-detail or points-based rule and counts every error. Younger children can join in if an adult reads the steps aloud.
No. Every card has its color written on it as a word, so the activity works printed in black and white. You can also draw the 12 stickers by hand from the card list.
Go on to the test cards anyway, because a rule is only known to work once it has been tested on new cases. Then ask whether someone could have guessed a different rule from the same six cards. Try the older-children variation for a harder hidden rule.
A machine-learning system finds a pattern in labeled examples and uses it to predict new ones, which is what your child does with cards 1 to 6. The test cards show whether the pattern was the right one. When it was not, adding new examples or changing what the rule looks at is how the mistake gets fixed.
Every machine’s hatch stays locked until your child commits a guess, so they think before they look. They change one thing at a time so the test is fair, and prove what they found on a case the machine has never seen. Hints never count against a child, and finishing a mission never claims mastery.
No. At ages 8 to 10 there’s no Python and no typing: answers are picture choices and sentence tiles, and every instruction is spoken and captioned. At 11 to 13, children read, predict, change and test a small program. At 14 and up, advanced code is optional.
The first missions are free; membership comes after. Places are limited: we email you when your family's place opens.