# Eating for a Better Planet

Look at the cards below.

Use the cards to answers these questions:

- Arrange the 9 foods in ascending order of emissions per portion.
- Without doing any calculations, try to put them in ascending order of emissions per calorie.
- Use a calculator to check your ordering.

Do the same for litres of water per gram of protein.

Which other measures could you use to order the foods? Which do you think is the "best" food?

You can download a complete set of cards, and use them to play "Top Trumps".

You can find more information about the cards here.

This problem is based on the work done by Sarah Bridle and her colleagues at "Take a Bite out of Climate Change".

You can hear about Sarah Bridle's mathematical journey in this "The Life Scientific" podcast

If you want to, you can use the equivalent minutes of driving figures per portion (the numbers in the black circles) to order the foods in order of increasing emissions.

To find the emissions per calorie divide the grams of CO_{2} emissions by the number of calories. For example the calcuation for eggs would be:

$$\dfrac{470}{143}\approx 3.28 \text{ grams CO}_2 \text{ per kCal}$$

This problem is based on the work done by Sarah Bridle and her colleagues at "Take a Bite out of Climate Change".

There are opportunities here to discuss compound measures, and what might be a good measure of the "best food". Students can also be asked to consider what other information might be useful.

On this page there are some suggestions about how the complete set of Climate Food Flashcards can be used in the classroom. You can download a set with front and back sides via dropbox, or there is a pdf version with 8 cards per page.

You can find more information about over 100 different types of food in this spreadsheet, whcih might be useful for futher investigations.

This problem is one of a collection designed to develop students' carbon numeracy; we hope it will encourage students to think about the issues surrounding climate change. You can find the complete collection here.