An explanation of how leaves work as a plant's food factory, converting sunlight into food for the plant in a process called photosynthesis. We see the result of an experiment in which the leaves of a plant have been removed. What happens when the leaves of a tree get infected with a disease? A tree surgeon explains the tree can't produce food if the leaves die.

First broadcast:
8 October 2007

Pupils may conduct a similar investigation, changing the number of leaves and measuring how fast each plant grows. It may lead to other experiments such as changing the amount of light plants receive and seeing the affect on growth and health. Children may also use the information from this clip to help them construct guides on how to grow plants well.