Category: Visual Methods

Percentages Using Ratio Grids

If you are not already confident using RATIO GRIDS then watch this video first!

What is 35% of £14?

What is 15% of £85?

My savings target is £5500. I have saved £2640. What percentage have I saved?

Jo scored 65% in a test. She scored 26 marks. What was the test marked out of?

A tree was 15m tall in January. Now it is 18m tall. What is the percentage increase in height?

Another tree has grown 15% since January. It is now 46m high. What was its height in January?

Now try some problems yourself:

notes-sheet-6-percentagesDownload

Ratio Grids Topic Overview

I invented “Ratio Grids” to help students who struggle with Proportional Reasoning. The philosophy includes:

  • All proportional reasoning sums are essentially the same – times 2 numbers and divide by a third. If one of the numbers is one, then it’s just a multiply or a divide.
  • Students who get used to working a problem “forwards” often struggle to work backwards, but mathematically there is no difference!
  • Skills gained working with ratios can be applied to shopping, percentages, similar shapes, stratified sampling, speed, density, and other “per” problems, Direct and Inverse proportion, currency conversions, unit conversions and the Sine Rule, without learning shed loads of new stuff.
  • Students often get in a muddle because they do sums and lose hold of the units of numbers so although they get a correct answer they don’t realise what it means! Ratio hold the units of numbers as well as the numbers themselves.
  • Students sometimes try to mix different units inappropriately in their working. With ratio grids this is much less likely.
  • Start at the beginning with the Introduction to Ratio Grids

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