Take two or three hands-up answers, not open call-outs. You are fishing for two things: that the question asks 'how many bottles fill the jug' and that the answer will be a plain count of bottles (not ml). Do not solve it here — this is just to prime the class to read a problem before grabbing numbers.

Habit throughout: read, spot the signal word, then decide add or subtract. Put a short question between each so the watching room stays with you.

Ribbons: signal word 'joined' means add. Both already in cm, no renaming. Ask which word tells us to add, take two hands. 45 + 30 = 75 cm; stress the answer keeps its unit, 75 cm not 75.

Apples: the make-or-break one. Signal 'eaten' means subtract, but the board still shows 2 kg. Ask can we take grams from kilograms as they stand, take a hand. Rename 2 kg to 2,000 g in front of them, then 2,000 - 750 = 1,250 g, tidy to 1 kg 250 g. The rename is the pupil's first job on the interactive too, not done for them.

Juice: signal 'each' with three cups means add three lots. Ask them to predict under or over a litre, take two hands before revealing. 250 + 250 + 250 = 750 ml, which is three-quarters of a litre, still under a whole litre.

This round is for talking it through together — pupils take turns at the board and the class agrees or corrects out loud. Reveal the problems one at a time rather than all at once, so nobody is trying to hold three in their head.

For each problem, freeze before the numbers: which word tells you the operation, and are the units the same? The ribbon problem needs 1 m renamed to 100 cm; the flour problem needs 1 kg renamed to 1,000 g; the jug problem needs 1 l 500 ml renamed to 1,500 ml. The board problem shows the mixed unit each time, so the pupil at the board must do the rename first. Revoice a strong answer as 'so you renamed first, then you subtracted — that's the whole trick'. Rotate three or four pupils across length, weight and capacity so everyone sees a rename in at least one.

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.

The practice set climbs on purpose: the first is same-unit adding (no rename), then a length problem needing 1 m → 100 cm, then a weight problem needing 1 kg → 1,000 g, then a capacity problem needing 1 l 500 ml → 1,500 ml. Each board problem shows its original mixed unit, so the pupil at the board performs the rename themselves. Ask 'do the units match yet?' before every calculation. Watch for pupils reaching for the numbers before reading the signal word.