Take three hands-up answers, not open call-outs. Give five seconds of quiet think-time first. Don't confirm right or wrong yet — the point is to surface that some pupils already reshape the numbers (e.g. 25 × 16 = 50 × 8 = 400) while others start the long algorithm. Hold that tension; the lesson resolves it.

Double-and-halve, 25 × 16: halve one, double the other, answer stays put. Panel one halves 16 to 8; panel two doubles 25 to 50, so 50 × 8 = 400, same as 25 × 16. Show the ÷2 and ×2 side by side so they see them cancel. Ask: if 16 halved again to 4, what would 25 become? (100.)

Compensation, 6 × 99: 99 is awkward, 100 is friendly. Panel one does 6 × 100 = 600; panel two takes back one lot of 6 to reach 594, because 99 is one short of 100. Stress we never work with 99 directly. Same round-and-adjust idea they've met, now in multiplication.

Partition, 35 × 12: split 12 into 10 and 2. Panel one does 35 × 10 = 350, panel two does 35 × 2 = 70, add to get 420. Name this as the partial-products idea from the area model. Splitting never changes the answer.

If the interactive won't load, write each pair as two-line jottings on the board.

Read the three snapshots as three separate results, not as a single machine feeding into the next — each panel shows one independent halving with its own fixed number in and number out.

• Cover the third snapshot so it is hidden, then ask the class to predict 18.
• Say the mantra: 'dividing by 8 is halving three times, because 2 × 2 × 2 = 8'.
• Link back: dividing by 4 is halving twice.

If the machine fails to load, write the three halvings on the board by hand: 144 → 72 → 36 → 18.

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

Start with the probe-and-build demonstration in the description: send 1 through the × 50 machine so the class sees 50 come out, then send 10 to see 500, and say aloud 'so the hidden rule would be × 50'. This models the exact deduce-and-build mechanic the Class Challenge needs.

The machine holds × 50 for the first problem (24 × 25 reshaped to 12 × 50): send 12 through and 600 appears. For the remaining three, retype the rule for each: × 50 again for 7 × 49 (send 7, get 350, then say aloud you take back 7 to reach 343), ÷ 2 twice for 96 ÷ 4, and use partition jottings on the board for 45 × 11 (450 + 45 = 495). Before each reveal, ask 'which strategy would you reach for here, and why?' Watch for pupils defaulting to the column method for 45 × 11 — steer them to partition. The 7 × 49 case is the compensation lock-in: many will want 7 × 40 + 7 × 9; revoice that as 'partition is a fine second route — is compensation faster here?'