Here are three instruments, and on each one the pointer has stopped between two numbered marks: a ruler, a measuring jug and a weighing scale.

None of them lands neatly on a number. So what is each one actually reading? And how would you work out the little marks that have no number written on them?

The interactive shows a ruler, a measuring jug and two weighing scales in turn. The same trick works every time — count the spaces in one gap, work out what one space is worth, then read the pointer. Watch where each pointer lands and what one small space is worth.

Before you go hands-on, let's bring one more ruler reading up on the board and work it through together as a class.

Now you measure. Each group has a real ruler, a part-filled measuring jug and a set of weighing scales.

Work through them in order. First the ruler: measure the glue stick. Then the jug: read the water level. Then the scales: weigh the object on your table. For each one, say out loud what one small space is worth before you read the pointer. Keep your eye square to the scale.

If your class has only one or two sets of scales, take turns at a scales station while the others start on the ruler and jug. Any group without a real jug or scales can use the printed instrument cards instead — the reading skill is exactly the same.