Run the thumbs read first so every pupil commits to a position before any voice goes up. Then take three hands-up answers, not open call-outs. Listen for pupils who say 'you can't take 75 from 5' — that's the live misconception that the lesson resolves. Don't reveal the answer; this question is the hook into the model step.

Walk each example aloud one at a time, in order. Pause on the regroup mark in each one.

• 4.5 − 1.75 — say it out loud: 'we add a trailing zero so 4.5 becomes 4.50, then we borrow a tenth and break it into ten hundredths.'
• 0.6 − 0.27 — emphasise the trailing-zero trick again so it's clearly a habit, not a one-off.

Pacing lever between examples 2 and 3: pause and ask the class, 'will the same trick work when the top number is a whole number with nothing after the point?' Take a quick thumbs read (up = same trick, sideways = something new), then run example 3 so pupils watch with a prediction in their heads.

• 1.0 − 0.85 — this is the chain. Narrate the link: 'one whole becomes ten tenths; one tenth becomes ten hundredths.'
• 5.005 − 0.999 — 'the rule never flinches — it just reaches one column further.' This is the load-bearing moment of the lesson.

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

Set up 3.2 − 1.45 on the board. Have one pupil add the trailing zero to make 3.20, then a second pupil work the hundredths column (it needs a regroup), then a third pupil work the tenths and units. Pause after each column and ask the class what the next digit will be before it lands.

If time allows, run a second example with the class — try 0.7 − 0.34 using the same step-by-step rhythm. Listen for the misconception 'you can't take 4 from 0' — revoice it as 'right, that's our cue to regroup from the tenths column.'

This round is the practice bank — pupils take turns at the board, check each answer, and the class confirms before moving on. The same five-problem bank reruns at home as tonight's homework, so keep the board work brisk rather than over-explaining.

Engagement protocol: the pupil at the board taps a digit; before each next digit lands, ask the class what it will be and take a quick answer. This keeps every watching pupil tracking each column.

Watch for the chain in problem 3 (1.0 − 0.73) — the regroup runs from units → tenths → hundredths and is the make-or-break moment. Problem 4 (5.005 − 0.988) extends the same chain one column further to thousandths; let pupils articulate 'same trick, one more column' before they tap.

If pacing allows after the bank of five, pull one extension problem from the extension bank for a final stretch question to round off the lesson.