Math · Stage 4
Solve deduction and working-backwards multi-step puzzles
Two detective moves: read the clues to deduce what must be true, and start from the ENDING to work backwards to the start — undoing each step in reverse.
✦ Math📘 Stage 4 · S4⏱ ~10 min🧒 Ages 8–9★ Free to start
I can solve deduction and working-backwards multi-step puzzles.
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Kavi the Detective 🔎
Kavi pulls on a tiny detective hat. "A good puzzle doesn't tell you the answer — it leaves clues," hoots Kavi. "Sometimes I deduce: each clue crosses options out until one is left. And sometimes I work backwards — I start at the end and undo every step until I reach the start 🔎."
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What your child will learn
1Forwards tells you the end — backwards finds the startA puzzle often gives you the ENDING and hides the START. Tap each card to see the two directions.
2Undo an 'add' by subtractingKavi thought of a number, added 8, and landed on 20. To find the start, do the opposite — take the 8 back off. Tap Step → to watch 20 − 8.
3Deduce: let each clue cross one outSecret number on a card: 2, 5, or 8. Tap each clue to see what it removes.
4Match each friend to their fruit from the cluesClues: Ben likes bananas. Mei does not like apples. Everyone likes a different fruit. Drop each friend in the right box →
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A peek inside
Kavi thought of a number, added 6, then took away 4, ending at 12. What was the start?
work backwards: 12 + 4 = 16, then 16 − 6 = 10
Try this at home: Undo one step: I added 9 to a number and got 21. The start was 21 − 9 = __
Ready to play and learn?
Start the free interactive lesson, or print the handout for screen-free play.
Part of Math · Stage 4 · S4 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.