Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about food tests (GCSE and Key Stage 3)
Where to start?
Use a magnet to extract iron metal from a packet of iron fortified cereals. This provides an introduction to the idea that food is composed of different substances and this can then lead to a discussion of what the nutritional label tells us about what else is in cereal.
Testing foods for carbohydrates, fats and proteins
GCSE worksheet on testing for carbohydrates, lipids and proteins. This activity should be done once students have a secure understanding of how to test foods for proteins, carbohydrates and fats. The simple context of urine tests helps students to understand the rationale behind wanting to test for different food groups. Once students have been introduced to the challenge, ask them to create a results table. This will focus their plan of what to do during the experiment. Only when students have completed a suitable table can they carry out the experiment.
Linking chemistry to the food tests
What is happening to the copper (II) ions in the Benedict’s test? Why do we need to heat the solution? Why does starch produce a negative result with Benedict’s solution unless acid is added? Why are lipids insoluble in water but soluble in ethanol?
- How could you make each food test quantitative?
- Are all proteins the same?
- Is there a difference between a lipid and a fat?