Take two or three hands-up answers, not open call-outs. Steer toward the idea of shrinking every length by the same amount. Do not reveal the words 'scale' or 'scale drawing' yet — that lands in the next step.

Read the first scale aloud: one centimetre on the page stands for one metre in the room. Point at the 6 m wall, then the 6 cm line, and ask what stayed the same. The 1 cm = 1 m case is deliberately the easy anchor. On the 1 cm = 2 m plans, hold out for the divide by the scale step and run it twice (8 ÷ 2, then 6 ÷ 2) so the class sees the method more than once — this is where pupils slip, expecting the number to stay the same again.

Talk this one through together — one pupil measures the long wall with the metre stick at the front while the whole class follows aloud; a second pupil marks the line, and the class agrees or corrects. Circulate is not needed here; stay at the front. The width and doorway are given ready-made so you only measure once and protect the time budget. Name the actual lengths as they are found — the long wall is about 6 m, so 6 cm at 1 cm = 1 m — then run the same wall at 1 cm = 2 m so the class rehearses dividing by the scale before the challenge. Keep the board work brisk.

This is the practice round — pupils take turns at the board, the class checks each answer, and confirms before moving on. Keep the board work brisk rather than over-explaining. The last one is where the class sees what the sequence was building to: at 1 cm = 2 m you divide each length by 2, so 8 ÷ 2 = 4 cm and 4 ÷ 2 = 2 cm, halving every drawn length. Show the division on the board, not just the answer. Ask the class to predict the new hall size before revealing it; waiting pupils watch the board and call the prediction.