A blog about teaching and learning in a maths classroom.

Monday, 17 January 2011 | 6 Comments

When introducing the topic of ‘ratio’, I use the mixing of cordial as an illustration that most kids get.

The idea of using 1 part of cordial to 4 parts of water makes sense to them – and they get the idea of equivalence when you mix the cordial in a different sized container (I use the examples of using cups to fill a bottle for a picnic, and using buckets to mix a big batch for a party).

Recently Cottee’s Cordial started making their cordial concentrate in 1 L rather than 2 L bottles. Doubling the strength of the concentrate with the instruction, “Just Use Half”. See ‘Products’ on the Cottee’s Cordial web-site.

Rather than explaining how I’m thinking of using this in class – because to be honest, I’m not sure – I’m going to pose a WCYDWT? ala Dan Meyer.

So, **what can you do with this?** Your suggestions in the comments.

(click on images to view larger)

A set of photos is in the zip file below. High resolution versions are available on Flickr.

Cordial
ZIP, 754 KB

This work is licensed under a Creative Commons License (?).

Posted in • Lesson Idea • Ratio • Media • Photo • What can you do with this? | Short URL: http://mths.co/2097

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**Simon Job** — eleventh year of teaching maths in a public high school in Western Sydney, Australia.

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