Year 6 Maths: How to Solve SATs Problems on Converting Units

Year 6 pupils are expected to convert between familiar units of measurement and use those conversions to solve problems. This is an important part of the UK National Curriculum for mathematics at Key Stage 2, and it appears in different forms in the KS2 SATs: as a straightforward conversion, within a multi-step calculation, or in a real-life context such as distance, mass, time or capacity. With a clear method and regular practice, children can learn to spot what a question is asking and choose the right calculation.

What Year 6 pupils need to know

The National Curriculum expects pupils to use, read, write and convert between standard units, including kilometres and metres, metres and centimetres, centimetres and millimetres, kilograms and grams, litres and millilitres, and units of time. They should also solve problems involving these measures, including calculations with decimal notation. For example, pupils may need to recognise that 2.4 kg is 2,400 g, or that 3.5 km is 3,500 m.

Some conversions are based on multiplying or dividing by 10, 100 or 1,000. Others, particularly time, use different relationships: 60 seconds make a minute, 60 minutes make an hour, and 24 hours make a day. Children should understand these links rather than rely only on a memorised rule. That understanding helps them check whether an answer is sensible and cope when a SATs question combines units or presents information in an unfamiliar way.

The key idea: make the units match

A reliable first step is to identify the units in the question and decide whether they need to be made the same before calculating. If a problem asks for the total length of a 1.6 m ribbon and a 45 cm ribbon, the values cannot be added as they stand. Pupils can convert 1.6 m to 160 cm, then calculate 160 cm + 45 cm = 205 cm. Alternatively, they can convert 45 cm to 0.45 m and find a total of 2.05 m. Both methods are correct, provided the units are consistent.

Encourage children to write the unit beside each number. This simple habit makes it easier to notice a mismatch and reduces the risk of giving an answer in the wrong unit. Before calculating, they can ask: “Are these quantities in the same unit?” Afterwards, they should check whether the answer is a reasonable size. A total length of 205 metres would be unlikely for two short pieces of ribbon.

Converting metric units with confidence

For most common metric conversions, pupils can use place value. Moving from a larger unit to a smaller unit means the numerical value gets larger: 1 metre is 100 centimetres, so 3 metres is 300 centimetres. Moving from a smaller unit to a larger unit means the numerical value gets smaller: 450 millilitres is 0.45 litres.

Place-value grids and number lines can make decimal conversions easier to see. For example, 2.35 m is 2 m and 35 cm, which is 235 cm. Children can also think of 2.35 m as 2.35 × 100 cm. Whichever method they use, they should pay attention to the decimal point and the number of places involved. A common error is to add or remove zeros without considering the size of the unit.

Practical measuring supports this learning. At home or in the classroom, children can estimate and measure the length of a table, the mass of a bag of rice or the capacity of a bottle. Ask them to record a measurement in one unit and convert it into another. Real objects help connect written conversions to quantities children can picture.

Handling time conversions

Time questions need particular care because the units do not follow the metric pattern of tens. To convert 2 hours 35 minutes into minutes, pupils should calculate 2 × 60 = 120 minutes, then add 35 minutes to get 155 minutes. To convert 150 minutes into hours and minutes, they can find how many groups of 60 fit into 150: two hours, with 30 minutes left over.

In SATs problems, time may appear in a timetable, journey or event schedule. Children should read carefully to see whether they need elapsed time, a start time or an end time. Drawing a simple timeline can help. For example, to find the time from 9:45 am to 11:20 am, pupils can count on to 10:00, then to 11:00, then to 11:20. That gives 15 + 60 + 20 = 95 minutes, or 1 hour 35 minutes.

A step-by-step approach to SATs questions

When children meet a measurement problem, encourage them to read it twice. On the first reading, they should identify the situation and what is being asked. On the second, they can underline the measurements and circle the units. They should then decide whether to convert before calculating, choose a method, and write the answer with its unit.

For example, a recipe uses 750 ml of milk and 1.2 litres of water. To find the total in millilitres, convert 1.2 litres to 1,200 ml, then add 750 ml to get 1,950 ml. If the question asks for the answer in litres, pupils can convert 1,950 ml to 1.95 litres. The important detail is to follow the unit requested in the question, not just the unit that feels easiest to use.

Some questions require more than one step. A pupil might need to convert a distance, calculate the cost per kilometre, then compare two journeys. Encourage them to write one calculation at a time and keep track of units at every stage. If a problem includes extra information, children should decide which details are relevant rather than trying to use every number they see.

Common mistakes and how to address them

Children sometimes multiply when they should divide, or divide when they should multiply. A useful sense check is to remember that the number gets larger when expressed in a smaller unit, and smaller when expressed in a larger unit. For instance, 4 kg must be more than 4 g when both are written as grams and kilograms respectively: 4 kg is 4,000 g.

Another frequent issue is treating time like a metric measure. Remind pupils that 1.5 hours is 1 hour 30 minutes, not 1 hour 5 minutes. They may also forget to include a unit in the final answer or overlook whether a question asks for metres, centimetres, hours or minutes. A quick final check can catch these errors.

Making practice useful and manageable

Short, regular practice is often more effective than a long session focused only on conversions. Mix direct questions with word problems so children practise both the calculation and the decision about which units to use. Worksheets can provide a helpful structure: begin with familiar conversions, then move on to mixed-unit problems and SATs-style questions that involve several steps.

When checking answers, ask your child or pupil to explain how they know which operation to use. If an answer is incorrect, focus on the reasoning: did they choose the wrong conversion, misplace a decimal point, or calculate accurately but use the wrong final unit? Understanding the cause of an error is more useful than simply repeating the question.

Keep the tone calm and encouraging. Year 6 pupils are preparing for assessments, but they also benefit from seeing measurement as a practical skill used in everyday life. Cooking, reading a journey time, comparing product weights and measuring a room all offer natural opportunities to revisit the same ideas.

Conclusion

To solve Year 6 SATs problems on converting units, children need secure knowledge of common metric relationships, a separate strategy for time, and the habit of checking that units match before calculating. Encourage them to show their working, label measurements and review whether each answer makes sense. With practical examples, targeted worksheets and steady revision, pupils can build the confidence to tackle both straightforward conversions and more demanding measurement problems.