How much of our food crops are lost to disease? Lesson starter

This is a simple and easy starter to encourage students to understand the impact that plant disease has both on the world’s poorest farmers and on consumers in the UK.

Fill a bowl with your choice of ‘crop’. This should ideally be a foodstuff that looks relatively close to its unprocessed form, such as rice and coffee beans.  It should also be a foodstuff that your students can relate to – cocoa beans and coffee beans go down well.

The full bowl represents the total potential harvest. Ask a student to pour away (into another bowl) the amount that they think is lost to plant disease. Students tend to underestimate losses. You can ask the rest of the class if they think the student’s guess is right.

Then correct the amount yourself, either by pouring away more ‘crop’, or by adding it back in. Show students the amount of the crop lost to disease, and how much the farmer is left with.  Discuss what impact they think this has on the price of goods in the supermarkets. Students may have noticed, for example, that chocolate bars are getting smaller, and that prices are rising.

By pouring away the crop, students gain a more visceral understanding of a farmer’s losses.

We have selected three crops as an example. See the attached document for more details.