Percentage increase in engineering
A collection of resources to provide ideas for setting percentage increase in the context of engineering, together with materials to support the teaching of this topic.
'Stretchiness' models one way in which engineers use their knowledge of mathematics to investigate the properties of materials. Here students investigate the stretchiness of jelly sweets, and in doing so this brings in the idea of repeated percentage change and measuring skills.
There are two supporting resources. 'Using Percentages to Increase Quantities N7' is a resource from the DfE Standards Unit that links fractions, decimals and percentages, before going on to introduce multipliers for percentage increases and decreases. 'Incredible shrinking dollar' uses a video of repeatedly photocopying a dollar bill to introduce the idea of repeated percentage change.
Stretchiness
This Cre8ate maths activity draws on measuring stretchiness which involves the collection of real data, calculating percentages and experimental design.
This resource models one way in which engineers use their knowledge of mathematics to investigate the properties of materials. Here students investigate the stretchiness of jelly sweets, they are provided with a prompt card which suggests that they consider the condition of the material, length of time that the stretch should be applied and the type of sweet being used.
The mathematics involved includes percentage increase, measuring and working systematically.
Using Percentages to Increase Quantities N7
In this resource from the DfE Standards Unit, is ideal to use prior to working on the 'Stretchiness' activity. Links are made between fractions, decimals and percentages. Percentage increases and decreases are shown using multipliers and misconceptions such as a the results of a 50% increase followed by a 50% decrease are addressed.
Incredible shrinking dollar
A video shows a dollar being placed on a photocopier, the scale on the photocopier is shown to be 75%. Once the photocopy prints out, it replaces the dollar on the photocopier and the process is repeated three times. What will the dollar bill look like after getting reduced that many times?
This would make an ideal supplement to the 'Stretchiness' activity, showing repeated percentage changes.
