Idea 18of 22Builds onBig unit to small unit: multiply
Decimals in measurements
What does 1.5 m mean, in centimetres?
Today you'll discover
- what the .5 stands for
- how to convert a decimal measurement
- a common slip to avoid
Think firstA skipping rope 1.5 m long
A skipping rope is 1.5 m long. How many centimetres is that?
Decide first, then press Next. Look at the half piece at the end.
A skipping rope drawn as a bar, 1.5 m. Under it, one 1 m tile and one 0.5 m tile; then the metre marked 100 cm and the half marked 50 cm, 150 cm in all. The working reads 1.5 m = 150 cm, 1.5 × 100 = 150. The last step shows 2.5 L of water.
See the whole ideathe big idea and the key word, in one place
The big idea
A decimal is part of a unit: 1.5 m is 1 m and half a metre, 150 cm.
Easy to get wrong1.5 m is not 1 m 5 cm. The 5 is in the tenths place: 5 tenths of a metre is 50 cm.
HeightsHeights are often written this way: a Grade 5 student might be 1.4 m tall, which is 140 cm.
Key word
- decimal measurement
- a measurement with part of a unit after the point, like 1.5 m
Ready to use it?
- Write a decimal measurement in a smaller unit.