Give ten seconds of quiet think-time before any hands go up. Take two or three hands-up answers for the biggest, then two or three for the smallest. Don't confirm the rule yet, that is what Watch and Notice is for. If a pupil offers 753, revoice it as a good guess to test, not the settled answer.

753 from 3, 7, 5: biggest card in the biggest column. Point at the 7 in the hundreds worth seven hundred. Biggest possible number.

357 from same cards: flip it. Smallest card 3 in hundreds, 5 tens, 7 in units. Stress the 7 losing almost all its value in the units.

406 from 4, 0, 6: the key one. Ask what goes wrong if we put the zero first, before revealing. Let them see 046 is just 46. So 4 hundreds, 0 tens, 6 units gives 406, the smallest three-digit number.

One at a time, don't rush to the third.

This round is for talking it through together — one pupil at the board per set and the class agrees or corrects out loud.

Send one pupil up per set. Ask them to say the largest card aloud before they place it, then build the biggest, then rebuild for the smallest. To keep the watching class with it through the middle set, turn-and-name: point at a seated pupil and ask which card goes in the hundreds and why, or revoice the board pupil's placement back to the room. Watch for pupils who put cards down in the order they were called rather than sorting by size — prompt which card is worth the most, and which column should it go in?

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.

For each set the whole-class task is two numbers: build the biggest, check with the ✓, then rebuild for the smallest and check again. The practice set below holds the biggest and smallest for each set. The 7, 0 and 3 set is the pause — ask where the zero can and cannot sit before the smallest is built. The 8, 8 and 1 set surprises pupils who expect three different digits; agree aloud that a repeated digit is fine.