Converting metric units | Year 5 Mathematics PDF Download

Converting Measures

• Converting measures is essential for various tasks. 
• For instance, if a recipe calls for 0.2 kg of butter but your scales only measure in grams, you need to convert the measure to ensure accuracy.

Kilograms and Kilometres

• The term 'kilo' originates from the Ancient Greek word for 'thousand' (chilioi).
• Therefore, 'kilometre' signifies 'thousand metres' and 'kilograms' denotes 'thousand grams'.
• Conversion Factors:
  • 1 km = 1000 m
  • 1 kg = 1000 g

Examples

Example 1: Converting 0.4 kg to grams
Sol: Method 1:

This bar model shows how 1 kg can be split into tenths.
Each tenth is worth 100 g. 0.4 is the same as four tenths (4/10).
By looking at the bar model, four lots of 100 g is 400 g.
0.4 kg = 400 g
Method 2:
Another way you could work out the answer is by multiplying by 1000 to convert 0.4 kg into grams.
0.4 kg x 1000 = 400 g

Example 2: What is 2500 m in kilometres?
Sol: Method 1:
The bar model shows that each kilometre is made up of two 500 metres.
There are five lots of 500 m in 2500 m, which is the same as km or 2.5 km. 2500 m = 2.5 km
Method 2:
You could use your knowledge of kilo meaning '1000' to divide 2500 m by 1000 to turn it into kilometres.
2500 m ÷ 1000 = 2.5 km

Millimetres and Millilitres

• In mathematics, the prefix 'milli' signifies 'one thousandth'.
• Therefore, 'millimeters' represent 'one thousandth of a meter' and 'milliliters' represent 'one thousandth of a liter'.
• Key equivalences to remember:
  • 1000 millimeters (mm) = 1 meter (m)
  • 1000 milliliters (ml) = 1 liter (l)

Examples

Example 1: What is 4000 mm in metres?
Sol: Method 1: 
The bar model shows that each metre is the same as 1000 mm.
So 4000 mm is the same as 4 metres.
Method 2: 
You could divide 4000 mm by 1000 to find the conversion to metres.
4000 mm ÷ 1000 = 4 m

Example 2: What is 8/10 of a metre?
Sol: Method 1:
This bar model shows how 1 m can be split into tenths. Each tenth is worth 100 mm.
8/10 is the same as 800 mm.
Method 2:
You could use your knowledge of finding fractions to find the answer - divide by the bottom and times by the top.
Use the conversion 1 m = 1000 mm
1000 mm ÷ 10 = 100 mm
100 mm x 8 = 800 mm