Write 305 large on the IWB and give five seconds of quiet think-time before any hands go up. Take three hands-up answers, not open call-outs. Then write two or three pupil-suggested three-digit numbers beside it and read each aloud together. Keep this brief, the columns get built properly in the next step.

Walk each example aloud, one at a time, pointing at each column.

• 247 — name each column in turn: two hundreds, four tens, seven units.
• Ten of one make one of the next — this is where the class builds the ten-times rule for themselves. Lay out ten loose ten-rods, count them aloud, then physically trade them for one hundred-flat on the mat. Ask 'how many ten-rods make one hundred-flat?' and take the answer from the class before confirming. Do the same with ten units for one ten-rod if time allows. The display shows the single hundred-flat the trade lands on.
• 408 — the zero in the tens column is the key moment. Point at the columns as you say 'if we forgot the zero and wrote 48, the 4 slides into the tens and the 8 into the units' so pupils see the slide on the board, not just hear it.
• 530 — the zero has moved to the units column; the number ends in nothing.
• 999 — ask 'what comes next?' and pause before letting anyone answer. This sets up the wrap.

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

Call a number under 1,000, then invite an individual pupil up to build it on the mat. Rotate four pupils across four numbers. Pick at least one number with a zero (e.g. 306 or 720) so the class has to reason about the empty column. After each build, ask the class 'does every column match the number we heard?' before confirming.

Pupils watching the board are checking the build, that watching is their part, so keep the pace brisk and revoice a good correction aloud. Four single builds with a quick class check is roughly nine minutes, not a quarter of the lesson.

This round is the practice bank — one pupil builds at the board while the whole class says the number and names the empty column aloud first, then watches the build being checked. Keep the board work brisk rather than over-explaining.

Run the four targets in order. For each, ask 'what is tricky about the zero here?' before the pupil presses Check, 308 has an empty tens column, 740 and 909 each have a zero too. Use the on-screen check tick as part of your narration: 'yes, that's it.' Pupils who finish thinking ahead can mouth the next number, no desk work in this step.

Recap the three points quickly using a number from the lesson (e.g. point back at 408 for the zero, and back at the ten-rods trade for the ten-times rule). Keep it to under two minutes so pupils move smoothly into their activity-book practice page.