Display the ruler-and-pencil photo as pupils settle. Take three hands-up answers, not open call-outs. Listen for anyone who reads the tiny marks between 16 and 17 — that is the millimetre reading we are after today. Don't confirm the answer yet; they will read their own objects next.

Real demonstration ruler at the front, not on screen. Lay each pre-measured object flat, one at a time.

Pencil: end at the 12 line plus four small marks — count the marks aloud, read as 12.4 cm or 124 mm.

Book 24.7 cm, then pencil case 19.5 cm — same routine, name both unit versions each time.

Parallax: lean deliberately to one side so the line seems to slip, then come back square-on. Say eye square over the mark and have them watch the difference.

Do not solve the Getting Started photo — they read their own objects next.

This round is for pupils to measure at their desks with their own rulers — circulate and catch alignment slips on the spot. The class reads aloud and you reconcile any disagreement as you circulate.

Look-fors as you walk the room:

• End at zero — many pupils start the object at the left edge of the ruler, not at the 0 mark. This is the most common slip.
• Eye-square lean — gently move a pupil's head straight over the mark when they read at an angle.
• Both unit versions — if a pupil only gives centimetres, ask and in millimetres?

Take a few readings aloud at the end; where two pupils disagree on the same kind of object, re-measure one together at the front.

These are the practice questions, run the six real objects as rotation stations at the front. First, teach the missing nearest-millimetre move with one concrete demo at the board before anyone rotates.

Worked between-marks demo (show end to end):

1. Lay a pre-chosen object so its end clearly sits between two mm ticks (e.g. just past the sixth small mark after 8, closer to that mark than to the seventh).
2. Eye square over the end. Name both neighbouring marks aloud: 8.6 and 8.7.
3. Decide which is nearer (here 8.6). Say: we take the nearest mark, not a half.
4. Board both unit forms: 8.6 cm and 86 mm.

Then pupils come up in turns and read each object they reach with their own ruler; they record straight into the three-column table they ruled in their maths copy. There is no printed sheet to prepare.

Pupils read as many objects as they can reach in the time rather than a fixed number; keep the rotation moving so as many as possible get a turn, and confirm each reading aloud at the end.

Approximate true lengths for confirming the final readings: crayon ≈ 8.6 cm (86 mm), eraser ≈ 4.7 cm (47 mm), glue stick ≈ 15.2 cm (152 mm), highlighter ≈ 13.8 cm (138 mm), marker ≈ 14.5 cm (145 mm), colour pencil ≈ 17.3 cm (173 mm). Your own objects may differ by a millimetre or two, what matters is that readings agree across the class.

• If you have more than one set of objects, run two or three parallel stations so more pupils read at once.
• Slip to watch: pupils inventing a half-millimetre (e.g. 8.65) or always rounding up when the end is between marks. Revoice: nearer mark only.

Keep this brisk. The millimetre-reading skill feeds straight into the unit-conversion lesson that follows.