Year 3 Maths

maths owl

Measuring Length

measuring length - ruler with pencil and toy taxi

When you measure how long something is, you measure its length. Length can be measured in different units, such as centimetres and metres. Practise measuring different objects in centimetres, using tools like a ruler or a tape measure.

Most things are not an exact number of centimetres long. Sometimes you just need to estimate about how long something is. For example, rounding to the nearest centimetre, the pencil below is about 14cm long.

At home, you may have a tape measure that is 100 centimetres long. 100 centimetres is also called a metre. At school, you may have a ruler that is 100 centimetres long, called a 'metre rule'. Now why is it called that?

100 cm = 1 metre

Practise measuring in metres and centimetres. You might start by measuring how tall you or your friends are. Would it be easiest to use a metre rule, a tape measure or a ruler? What tool should you use to measure the width of a book?

Do you see that this ruler has numbers on the top that are closer together than the numbers on the bottom? The numbers on the top, that you used to measure the pencil, measure centimetres. In the UK, we use centimetres and metres to measure a lot of things. But we can also use another set of measurements, called inches and feet, to measure length. A centimetre is shorter than an inch; it's not quite half an inch.

Inches are shown on the bottom of the ruler. They are upside down because you should turn the ruler the other way around to measure things in inches. There are 12 inches in 1 foot.

The toy taxi is along the side of the ruler that measures in inches. How long is the toy taxi in inches? It is about 3 inches long.

If you have a ruler or tape measure, check to see if it has centimetres and inches, then practise measuring some objects in both types of measurement.

This activity is adapted from pages 260 - 261 of What Your Year 3 Child Needs to Know, which can be purchased here.