Take three hands-up answers, not open call-outs. Listen for whether pupils reach for 1,000 g = 1 kg. Do not confirm yet — the ladder in the next step makes it visible.

Work these four snapshots live on the ladder, one at a time; pause on each before the reveal and pull an answer from the class.

• 2,500 g → 2.5 kg — point to the digits sliding three columns; the point does not move. Name each crossed column as × 10 so three columns builds to × 1,000.
• 0.75 kg → 750 g — ask which way the digits go this time before revealing.
• 1,250 ml → 1.25 l — same 1,000 jump as mass; draw the parallel out loud.
• 3,500 g → 3.5 kg — hold out for pupils naming ÷ 1,000 as the move, and linking it back to 'kilo means a thousand'.

Talk this one through together — pupils take turns at the board and the class agrees or corrects out loud. Before each Check, ask the two prediction questions: which way do the digits shift when we go from grams to kilograms? and how many place-value columns do they move each time?

The four challenge rungs run as a set, taking the class from mass to volume in order. If the ladder does not carry the unit or category across on its own for a rung, set the From value and units for that rung before pressing Check — the labels on each challenge name the conversion you need.

Watch for pupils moving the decimal point instead of the digits — revoice the digits move, the point stays still. Hold out for the direction (× or ÷ 1,000) before each reveal.

This is the practice round — 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 the last one, work out the total in grams first (250 × 4 = 1,000 g) on the board so the class sees where 1,000 comes from, then convert. The challenge rung loads 1,000 g → kg so the ladder confirms 1 kg. Ask which is the tricky part — the multiplying, or the converting.