Module 5 (M5) – Geometry and measures - Reading scales on measuring instruments

This module builds on: M1 on metric units, fractions and decimals.

Scales are number lines which can be straight or circular. The number line is split into intervals with divisions marked.

You will see scales on measuring jugs, car speedometers, oven dials and many other measuring instruments.

When reading scales on any sort of measuring instrument, it is important to look at the divisions and intervals and work out what each interval is worth.

Example

The larger intervals on this kitchen scale go up in hundreds. You can also see there is a smaller interval in between each hundred.

This must be worth 50 g since it is the halfway point between hundreds.

The arrow on the dial is pointing at the smaller division between 700 g and 800 g, so the mass of the fruit must be 750 g.

Example

The large intervals on this scale go up in 1 kg. Between each large division there are 10 small intervals. Each small interval is worth 0.1 kg or 100 g.

The arrow is between 2 kg and 3 kg, on the third division after 2 kg, so the dial is showing 2.3 kg.