Here are four tools: a ruler, a metre stick, a balance and a litre jug. Four jobs wait for us today — a crayon, the yard, a schoolbag and a fish tank. Which tool fits which job?

First, estimate: how many centimetres long is the pencil? Share a careful guess.

Now the crayon. Estimate first. Then watch the careful measure: zero at the start, ruler straight, read the number at the far end.

Now think of two things from the shop: a bag of sugar and a milk carton. Kilogram is for how heavy something is. Litre is for how much liquid a container holds. Which unit for each — kilogram or litre?

One pupil at the board puts 1 kg on one pan. We try each object on the other pan: tin of beans, welly boot, big dictionary, schoolbag. Before each tip, the class predicts — heavier, lighter, or about the same as 1 kg?

Drag each job card onto the best unit and tool: cm with a ruler, m with a metre stick, kg with the balance, or litre with the jug. We will work these together.