New
New
Lesson 7 of 16
New
New
- Year 8
Increase by a percentage
I can calculate percentage changes (increase).
Lesson details
Key learning points
- A bar model can be used to find a percentage increase.
- A double number line can be used to find a percentage increase.
- A ratio table can be used to find a percentage increase.
Keywords
Proportionality - If two things are proportional then the ratio of part to whole is maintained and the multiplicative relationship between parts is also maintained.
Common misconception
A single digit percentage is incorrectly worked out by dividing by 10 and not 100 e.g 3% = 0.3. This error continues when increasing amounts e.g increase 40 by 3% has a multiplier of 1.3
Remind pupils that to covert a percentage into a decimal we divide by 100. This applies with increase too e.g 120% has a multiplier of 1.2
Using mini-whiteboards, for example, students must draw the same question but illustrated in different ways; ratio table, double number line or bar model. E.g Increase 800 by 55%. They can then decide which representation they prefer. Look out for efficient approaches e.g 50% + 5%
Teacher tip
Licence
This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
Loading...
Prior knowledge starter quiz
6 Questions
Q1.Match each percentage statement to its value.
Match each percentage statement to its value.
Q2.22% of 84 is .
22% of 84 is .
Q3.31% of 750 is .
31% of 750 is .
Q4.Which of the following calculations is equivalent to 12% of 300?
Which of the following calculations is equivalent to 12% of 300?
12 × 300
12 × 100
30 + 3
Q5.Match each calculation with the correct percentage statement.
Match each calculation with the correct percentage statement.
Q6.19% of 84 is .
19% of 84 is .
Assessment exit quiz
6 Questions
Q1.Increase 400 by 20%.
Increase 400 by 20%.
Q2.Increase 70 by 30%.
Increase 70 by 30%.
Q3.Match each percentage increase question with an equivalent question.
Match each percentage increase question with an equivalent question.
Q4.Match each statement with the correct multiplier.
Match each statement with the correct multiplier.
Q5.139% of 600 is .
139% of 600 is .
Q6.Increase 800 by 11% and then by 10%.
Increase 800 by 11% and then by 10%.
