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Cotmanhay Junior School

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Week 12 Converting units

National curriculum content


  • solve problems involving the calculation and conversion of units of measure, using decimal notation up to three decimal places where appropriate
  • use, read, write and convert between standard units, converting measurements of length, mass, volume and time from a smaller unit of measure to a larger unit, and vice versa, using decimal notation to up to three decimal places
  • convert between miles and kilometres


Lesson objectives


  1. Metric measures
  2. Convert metric measures
  3. Calculate with metric measures
  4. Miles and kilometres
  5. Imperial measures


What we want children to know


  • Read, write and recognise all metric measures for length, mass and capacity.
  • Use their skills of multiplying and dividing by 10, 100 and 1000 when converting between length, mass and capacity.
  • Pupils connect conversion (for example, from kilometres to miles) to a graphical representation as preparation for understanding linear/proportional graphs.
  • They know approximate conversions and are able to tell if an answer is sensible.
  • Know that 5 miles is approximately equal to 8 KM.


What skills we want children to develop

Use knowledge to solve reasoning and problem solving questions such as:


Write more statements


  • Chen, Megan and Sam have parcels. Megan’s parcel weighs 1.2kg and Chen’s parcel is 1500g and Sam’s parcel is half the weight of Megan’s parcel. Write down some other statements about the parcels. How much heavier is Megan’s parcel than Chen’s parcel?


Explain why


  • Mo thinks that 12,000 g is greater than 20 kg because 12,000 > 20 Explain why Mo is wrong.



Vocabulary/Mathematical Talk


  • Which units measure length? Mass? Capacity?
  • When would you use km instead of m? When would you use mm instead of cm?
  • Give an example of a length you would measure in miles or km.
  • Can you think of a situation where you may need to convert between miles and kilometres?
  • Put these in order of size: 1cm, 1mm, 1 inch, 1 foot, 1 metre. How do you know?
  • When do we use imperial measures instead of metric measures?
  • Why are metric measures easier to convert than imperial measures?