When we eat toast we are at the top of a very short food chain.  We are absorbing energy which a wheat plant originally absorbed from the sun in photosynthesis.

When we eat chicken we obtain energy from the chicken who obtained it from the wheat which in turn absorbed it from the sun. However, we only get a small amount of that energy. This is because energy gets used up at each stage of a food chain.

Meat production can be made more energy efficient by keeping the animals more intensively.  However, this raises welfare issues for the animals.

Are there other ways we could feed people efficiently without keeping animals intensively? Perhaps we could eat less meat, concentrating on free-range animals which eat foods like grass which we can’t eat?

The worksheet discusses the basic principles of food chains and pyramids of numbers that feed humans and how people can be fed efficiently while raising ethical issues relating to the use of science and technology.  Students are encouraged to formulate their own opinions, especially in relation to the different ways we use animals in producing food.

The worksheet, together with teachers’ notes, lesson plans and another set entitled Selective breeding of farm animals can be downloaded or ordered for free.