Research-based guidance and classroom activities for teachers of mathematics

Cooking numbers

This link takes you to Ratio Makes Sense, a SMILE mathematics pack on the National STEM Centre eLibrary. The relevant task is on pages 10-11.

Students have to work out different quantities of ingredients for different numbers of people. Some can be counted, such as eggs, but others have to be measured, such as flour. The smallest amount is the amount that can be made with one egg, so that could serve as a unit to construct a mini-recipe which can then be scaled for other quantities.

To prevent the task deteriorating into a grid-filling exercise, there needs to be discussion using the words ‘ratio’ and ‘proportion’ when it is completed. Quantities down columns and/or across rows can be compared multiplicatively, and the scaling between them discussed. Proportionality is embedded in the task because for any final amount internal ratios stay the same.

For this task, it is not so much the completion of the table as the reflective discussion which can move learners towards an understanding of the underlying reasoning.

Go to Ratio Makes Sense on the National STEM Centre eLibrary >>