Take three hands-up answers, not open call-outs. Do not settle it yet — the point is to create the puzzle. Write both candidate answers (20 and 16) on the board and leave them.

Settle the hook first on its own numbers: 4 + 6 × 2, so 6 × 2 = 12, then + 4 = 16. Correct answer is 16, not 20 — rub out the 20.

Then the three teaching examples, one at a time.

4 + 3 × 2: fresh numbers. Left to right gives 14 (wrong); rule is multiply and divide before add and subtract, so 3 × 2 = 6, then + 4 = 10. Point at both boards.

(4 + 3) × 2: pause before revealing, ask the class to predict. Brackets first, so 4 + 3 = 7, then × 2 = 14. Same numbers, brackets change the answer — this is the make-or-break idea.

20 − 12 ÷ 4: stress no bracket, so fall back to ranks. Multiply and divide share a rank, above add and subtract, so divide beats subtract: 12 ÷ 4 = 3, then 20 − 3 = 17. Divide goes first even though subtract is written to its left.

This round is for talking it through together — pupils take turns at the board and the class agrees or corrects out loud.

Ask a pupil to name which operation glows next before they tap it, and have the class agree. In 18 ÷ (1 + 2) × 4 the divide and multiply are equal rank, so after the brackets the divide goes first because it is on the left — this is the pause where left-to-right pays off. Revoice: 'same rank, so we read them left to right'.

This round is the practice round, pupils take turns at the board, press Check on each answer, and the class confirms before moving on. Keep the board work brisk rather than over-explaining.

The first two challenges deliberately share the same numbers so the class sees the bracket flip the answer from 17 to 45.

Placement demo (board only, before the final challenge). Expression 9 − 3 × 2, target 12. Work the sensible placements out loud:

• 9 − (3 × 2) = 9 − 6 = 3 (misses)
• (9 − 3) × 2 = 6 × 2 = 12 (hits)

Revoice the method: try each sensible bracketing, compare to the target, keep the one that matches. Slip to watch: pupils who try only one placement and guess.

The final task is the key pupil application. Answer is (8 + 4) × 2 − 1 = 23. Have pupils reason aloud which placement reaches 23, bracketing 2 − 1 gives 8 + 4 × 1 = 12, bracketing 4 × 2 gives 8 + 8 − 1 = 15, only bracketing 8 + 4 works (12 × 2 = 24, then − 1 = 23). The interactive confirms (8 + 4) × 2 − 1 when you press Check. The reasoning about which placement to choose matters more than a fast right guess.