Give five seconds of quiet think-time before any hands go up, then take two or three hands-up answers. Write 52 − 17 on the board in tens-and-units columns as you pose it. Don't resolve it here — the point is to leave the class sitting with the problem "there aren't enough units up top". The renaming move is built in Watch and Notice.

Hold to "rename" throughout, not "borrow" or "take back" — pupils should hear the ten changing form, not disappearing. (Borrow comes in next lesson as a synonym; today the value-preserving idea lands first.)

43 − 18: 3 too small for 8, so rename. Cross out the 4, write small 3 above it, put little 1 before the units 3 so it reads 13. Say one ten has moved over. 13 − 8 = 5, 3 tens − 1 ten = 2 tens, answer 25.

62 − 27: take a quick guess first — is 2 enough to take 7 from? Take one or two hands, stress no wrong answer, then reveal. Rename: tens 5, units 12. 12 − 7 = 5, 5 tens − 2 tens = 3 tens, answer 35. Walk the add-back check once: 35 + 27 = 62.

50 − 24: the make-or-break case. Top has 5 tens and a 0, no units — still rename. Tens drop 5 to 4, units become 10. 10 − 4 = 6, 4 tens − 2 tens = 2 tens, answer 26. Emphasise a zero on top does not stop us.

This round is for talking it through together — pupils take turns at the board and the class agrees or corrects out loud. Nothing is auto-marked here; the class settles the answer aloud before a digit is typed.

For each subtraction, ask first "are there enough units at the top?" and take a class answer before touching the rename cell. A pupil comes up, taps the rename cell to rename when needed, then fills each answer cell.

• 45 − 19 — rename needed (5 < 9).
• 63 − 28 — rename needed (3 < 8).
• 81 − 79 — the key one: rename needed, and the tiny answer (2) surprises pupils because the two numbers looked far apart. Draw out that a big-looking subtraction can leave a small difference.

This is the Class Challenge — pupils take turns at the board, the whole class watches, and everyone confirms each answer together before moving on. Keep the board work brisk rather than over-explaining.

• 38 − 15 — no rename (8 > 5); a deliberate contrast so pupils don't rename out of habit.
• 52 − 27 — rename needed.
• 70 − 34 — renaming from a top zero in the units.
• 91 − 58 — the hardest; rename, and the tens drop from 9 to 8.

Each pupil taps Check after filling the answer row; the class confirms the ✓ before moving on.