Look at this dial. The pointer has stopped between the 200 g mark and the 300 g mark. It is past 200 but it has not reached 300.

Is this right? A friend read it as "200 g". What would you say to them?

Before we read any pointer, we always ask one question first: how much is each little mark worth? The step size is how much each little mark on the dial is worth. On one dial each step might be 100 g; on another dial, each step might be 50 g.

Look at the dial on screen. Watch four readings in turn:

• a dial in steps of 100 g, with the pointer landing right on a printed mark;
• a dial in steps of 50 g that looks almost the same, but each little mark is worth only 50 g;
• a bigger dial in steps of 100 g. Here the numbers pass 1000 g. We know 1000 g is the same as 1 kg, so once we count past 1000 we rename it: 1500 g becomes 1 kg 500 g;
• a dial where the pointer stops halfway between two marks. When that happens, the weight is halfway between the two numbers too. Halfway between 700 g and 800 g is 750 g.

Notice how two dials can look almost the same, but the same pointer position means different weights once you know the step size.

First we learn how to find the step size by counting the little gaps on a dial. Then we read four dials together.

Watch this worked example on the board. Two printed numbers sit next to each other: 200 g and 300 g. The gap from 200 to 300 is 100 g in total. Count the little intervals (the small gaps) between those two printed numbers. There are 2 little intervals, so each step is worth 100 g ÷ 2 = 50 g. That is the step size. Only after we know the step size do we read where the pointer lands.

Now we try four dials together, one at a time. For each one, find the step size first by counting the intervals. Then read the pointer and say the weight:

• a dial with the pointer on a printed mark;
• a dial that looks similar to the first;
• a bigger dial where the numbers pass 1000 g, then rename the reading in kilograms and grams;
• a dial where the pointer stops halfway between two marks.

Now we work through these readings together on the board. Say the step size out loud before you read each pointer:

• a dial, read the pointer;
• another dial, read the pointer;
• a bigger dial that passes 1000 g, read the pointer and rename it in kilograms;
• a dial where the pointer stops right between two marks, read the halfway weight.