Give five seconds of quiet think-time before any hands go up, then take three hands-up answers, not open call-outs.

Don't reveal the answer yet. Listen for the different routes pupils describe (some add the 30 first, some round up to 40) — you'll name these as strategies in the next step.

Take each one slowly; the point is one sum, three routes.

Partition 47+38: +30 to 77, then +8 to 85. Say split 38 into 30 and 8.

Compensate 47+38: +40 to 87, overshoots, jump back 2 to 85. Stress +40 is easier than +38.

Bridge 47+38: +3 to the friendly 50, then +35 to 85. Round ten first makes the next jump easier.

Point out all three land on 85.

235+198: +200 to 435, back 2 to 433. Ask why adding 200 was easier than 198 — this is where compensating clearly wins.

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

Let the class decide the strategy before a pupil draws. For 56 + 27, some will partition (+20, +7); others will bridge to 60 (+4, +23). Both land on 83 — revoice that different routes reach the same answer.

If time allows, reset the line and let the class call a fresh two-digit sum to try the same way; the focus is matching strategy to numbers, not copying a worked example.

These are the practice questions — pupils take turns at the board, check each answer, and the class confirms before moving on. Keep the board work brisk rather than over-explaining.

Each challenge targets the fewest possible jumps (two). For the three-digit sums, compensating usually wins (235 + 198 in two jumps: +200, −2; 268 + 197 in two jumps: +200, −3). If a pupil reaches the answer in more jumps, accept it, then ask the class if there's a shorter route.

Keep this brief. Reinforce the one big idea: mental strategy is a choice that fits the numbers, not a single rule to memorise.