Watch three worked column-additions on the board. On each one, notice where the small carry-1 lands and which column it lands in. After each example, we name the column the carry lands in.

The third example is a deliberate contrast. Look carefully at every column as it lands, then say what makes this one different from the first two.

Example 1: 4,738 + 2,569 = 7,307

The classic three-regroup case. A carry lands above the tens, the hundreds and the thousands.

Example 2: 9,876 + 1,234 = 11,110

One carry triggers the next, all the way up — a cascade through to the thousands, with a brand-new ten-thousands digit at the very end.

Example 3: 5,000 + 4,999 = 9,999

Two big four-digit numbers, but watch each column: nothing regroups at all. The numbers are big, but the columns stay friendly.

Today we work through 6,847 + 3,956 together. One pupil at a time comes to the board and steps the algorithm column by column. Before each column is added, hands up: the teacher takes one prediction for the column total, then the rest of you show thumbs up to agree or thumbs sideways to change it before the pupil at the board taps to reveal.