Measurement, money and time
Measurement questions mix place value, decimals and problem solving with real-world units. Most errors come from two habits: calculating with mixed units, and treating time as if it were decimal. Fix those and this whole strand becomes reliable.
Converting metric units
Metric units are based on 10, 100 and 1,000, so converting is multiplying or dividing by one of those. Year 6 pupils convert between units of length, mass and volume using decimals to three places.
| Measure | Conversions |
|---|---|
| Length | 10 mm = 1 cm; 100 cm = 1 m; 1,000 m = 1 km |
| Mass | 1,000 g = 1 kg |
| Volume and capacity | 1,000 ml = 1 l |
- 2.5 km = 2,500 mConverting to a smaller unit: the number gets bigger.
- 750 g = 0.75 kgConverting to a larger unit: the number gets smaller.
- 750 g = 7.5 kgDividing by 100 instead of 1,000.
The quick check is to ask whether the number should get bigger or smaller. A kilogram is bigger than a gram, so there are fewer kilograms.
Imperial units
Year 6 pupils need approximate equivalences between metric and common imperial units, especially that 5 miles is about 8 kilometres. A double number line makes scaling easy: 5 miles = 8 km, 10 miles = 16 km, 15 miles = 24 km. Children should also recognise inches, feet, pounds and pints as units still used in everyday life.
Reading scales
Reading a scale means working out what each small division is worth before reading the value. Find two labelled numbers, work out the difference, and divide by the number of intervals between them. A jug labelled every 100 ml with four intervals between labels goes up in 25 ml steps. Assuming each mark is worth 1 is the most common error.
Money and measure problems
Most measure word problems are multi-step and need a unit conversion along the way. The golden rule is to convert everything to the same unit before calculating.
- 1.5 kg + 300 g = 1,500 g + 300 g = 1,800 gSame units first.
- 1.5 kg + 300 g = 301.5Adding mixed units.
- £2.50 + 75p = £2.50 + £0.75 = £3.25Pounds and pence in one unit.
Money answers are written with two decimal places (£3.50, not £3.5), which is a small point that costs marks in the SATs.
Time
Children read analogue clocks (including Roman numerals), and 12-hour and 24-hour digital times, and convert between them: 3:15 pm is 15:15. In time problems, the trap is that time isn't decimal: there are 60 minutes in an hour, not 100.
- 10:45 + 35 minutes → 15 minutes to 11:00, then 20 more → 11:20Count on to the hour first.
- 10:45 + 35 minutes = 10:80Treating time as decimal.
A time number line, counting on to the next hour and then beyond, solves almost every duration problem. Timetables add a reading challenge: practise finding information across rows and down columns before calculating with it.
In the SATs
Measurement runs through the reasoning papers: converting units, reading scales on jugs, rulers and thermometers, money problems, imperial conversions, durations, and reading bus or train timetables. Many questions are multi-step and carry two marks, so showing the conversion step matters.
Common mistakes
- Calculating with mixed units.
- Using the wrong conversion factor (100 instead of 1,000 for grams to kilograms).
- Assuming each mark on a scale is worth 1.
- Reversing the miles and kilometres relationship.
- Treating time as decimal, or misreading 24-hour times after midday.
Teaching ideas
Real equipment
Use real jugs, scales and rulers alongside worksheets. Reading an actual measuring jug at eye level teaches more than any picture.
Conversion washing line
Peg cards such as 1.5 kg, 1,500 g, 0.15 kg and 150 g on a line, then ask pupils to group the equivalent ones and order the rest.
Plan a day out
Give pupils a real bus timetable and a budget. They plan a trip, working out journey times, waiting times and costs. Every skill in this strand gets used.
Time number lines
Make drawing a time number line the standard method for duration problems until children can do it mentally.
Try it: five quick questions
SATs-style questions to use as a starter or a quick check. Tap to see each answer.
Convert 3.06 km to metres.
Show answer
3,060 m
Convert 450 ml to litres.
Show answer
0.45 l
About how many kilometres is 25 miles?
Show answer
About 40 km
A film starts at 18:40 and lasts 1 hour 35 minutes. When does it finish?
Show answer
20:15
Apples cost 45p each. How much do 7 cost, in pounds?
Show answer
£3.15
Free worksheets for this topic
Printable A4 PDFs with answers. Free to use in class or at home.
