Measurement: Metric and Imperial Units
In Year 5, pupils convert fluently between metric units of length, mass and capacity (for example millimetres, centimetres, metres and kilometres; grams and kilograms; millilitres and litres), using the fact that the metric system is based on powers of 10.
Method
- Learn the metric conversion facts: 10 mm = 1 cm, 100 cm = 1 m, 1000 m = 1 km, 1000 g = 1 kg, 1000 ml = 1 litre.
- To convert from a smaller metric unit to a bigger one (e.g. cm to m), divide by the conversion number; to convert from a bigger unit to a smaller one, multiply.
- Learn the key approximate metric-to-imperial equivalences given in a question, such as 1 kg is approximately 2.2 lb, or 5 miles is approximately 8 km, since exact conversion factors are not required to be memorised.
- When converting using an approximate equivalence, multiply the amount you have by the given conversion factor, checking the units match the direction of the conversion.
- Always check an answer is sensible: converting a small metric unit to a much bigger one should give a smaller number, and vice versa.
- When a problem mixes units (e.g. adding metres and centimetres), convert everything to the same unit before calculating.
- Show your working as a clear multiplication or division, since a correct method can earn a mark even if the final number has a small slip.
Worked example
A recipe uses 2.5 kg of flour. Using the approximate equivalence 1 kg is about 2.2 lb, estimate the mass of flour in pounds.
- Identify the conversion factor given: 1 kg is approximately 2.2 lb.
- Multiply the mass in kilograms by the conversion factor: 2.5 x 2.2.
- Calculate: 2.5 x 2.2 = 5.5.
- So 2.5 kg of flour is approximately 5.5 lb.
Practice questions
Type your answer and press Check to be marked straight away, or reveal the answer and mark yourself.
Q1Convert 4.5 km into metres.Show answer
Answer: 4,500 m (4.5 x 1000)
Q2Convert 380 cm into metres.Show answer
Answer: 3.8 m (380 / 100)
Q3Convert 2,600 ml into litres.Show answer
Answer: 2.6 litres (2600 / 1000)
Q4A plank of wood is 1 m 25 cm long. Write this length in centimetres only.Show answer
Answer: 125 cm (100 + 25)
Q5Using the approximation that 1 litre is about 1.75 pints, estimate how many pints are in 4 litres.Show answer
Answer: 7 pints (4 x 1.75 = 7)
Q6Using the approximation that 5 miles is about 8 km, estimate how many km a 15-mile journey is.Show answer
Answer: 24 km (15 miles is three lots of 5 miles, so 3 x 8 = 24 km)
Q7A bag of potatoes weighs 9 kg. Using the approximation that 1 kg is about 2.2 lb, estimate its weight in pounds.Show answer
Answer: 19.8 lb (9 x 2.2 = 19.8)
Exam-style questions
Written in the style of a KS2 Maths exam paper, with a full mark scheme.
A market stall sells apples by the pound. A customer buys a bag weighing 3 kg. Using the approximation 1 kg is about 2.2 lb, work out the weight of the bag in pounds.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
A cyclist rides 40 km. Using the approximation that 5 miles is about 8 km, work out how far the cyclist rode in miles.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
A water butt holds 70 litres. Using the approximation that 1 litre is about 1.75 pints, work out its capacity in pints.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
Free printable worksheet
Want more practice on paper? Download the measurement: metric and imperial units worksheet pack - 6 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
Next topics
Not quite what you needed?
Tell us what is missing on measurement: metric and imperial units, or which topic to write up next. Every request is read, and we reply to every one.
Build a full practice pack.
This topic is one of hundreds in the library - pick the ones a student needs and generate a printable PDF in minutes.