Take three hands-up numbers, not open call-outs. Jot each one on the IWB and slot it into a quick three-column frame as the class watches — this previews the hundreds column without teaching it yet.

Walk each example aloud, one at a time.

• 100 — make the trade explicit: ten tens become one hundred. This is the heart of the lesson.
• 234 — read every column in turn, left to right.
• 305 — the screen now states why the zero is written; point to the empty tens column and reinforce the 0 holds this column open so the other digits stay put.
• 470 — the empty column has moved to the units; the 0 holds that column.

Do not rush past the zeros — they are where most slips happen.

This round is for talking it through together — one pupil builds at the board while the class watches and the whole room reads the number back aloud, agreeing or correcting.

Call the four numbers in turn (216, 408, 530, 705). The mat starts empty so each pupil builds from scratch. After each build, the class reads it back column by column. Watch for pupils who build the digits but forget to read the hundreds as two hundred rather than two.

This round is the practice bank — 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 target, ask the class to predict what is tricky before the pupil builds it: 308 has a holding zero in the tens, 450 has a zero in the units, 909 has a zero in the middle with nines either side. Use the Check button as part of the narration — yes, that's it.