About cookies

The NCETM site uses cookies. Read more about our privacy policy

Please agree to accept our cookies. If you continue to use the site, we'll assume you're happy to accept them.


Personal Learning Login

Sign Up | Forgotten password?
Register with the NCETM

2.27 Scale factors, ratio and proportional reasoning

Created on 28 August 2019 by ncetm_administrator
Updated on 29 August 2019 by ncetm_administrator


Use bar modelling and ratio grids to reason about multiplicative relationships between two or more cardinal quantities, and explore correspondence problems. Extend understanding of scaling measures to make and interpret maps and scale/compare the dimensions of similar shapes.

Teaching points

  • Teaching point 1: Multiplication and division can be used to calculate unknown values in correspondence (cardinal comparison) problems.
  • Teaching point 2: Multiplication and understanding of correspondence can be used to calculate the number of possible combinations of items.
  • Teaching point 3: Scaling can be used to make and interpret maps.
  • Teaching point 4: There is a proportional relationship between the dimensions of similar shapes; if the scale factor and the dimensions of one of the shapes is known, the dimensions of the similar shape can be calculated; if the dimensions of both of the shapes are known, the scale factor can be calculated.



Comment on this item  
Add to your NCETM favourites
Remove from your NCETM favourites
Add a note on this item
Recommend to a friend
Comment on this item
Send to printer
Request a reminder of this item
Cancel a reminder of this item



There are no comments for this item yet...
Only registered users may comment. Log in to comment