Prior knowledge

• Explain what a ratio is, and how it relates to a fraction
• Understand the importance of comparing like to like in mathematics

Background

This is a brief  activity to support the mixing paint activity. The answers give a brief explanation of why the ratios need to be made equivalent before a comparison is made.

Note that students may come up with other ways of working out which mix gives the stronger colour, for example, 4:5 or 7:11 could be compared as fractions. The first has 4/9 or 44% blue, while the second has 7/18 or 39% blue – but this is getting tricky without a calculator (hint one third is 33.3%, so one eighteenth is about 5.5%).

Comments on the Exercises

Exercise 1
Asks students to show ratios on a number line and then determine the ratio with the highest red component.

Exercise 2
Asks students to determine from pairs of ratios which pair has the most blue, and then question 2 asks which pair has the more orange.