How does light affect growing plants?

Pupils need to know about the basic conditions that plants need to grow and also to provide simple explanations for why lack of light alters plant growth. This experiment helps pupils understand about light and plant growth and it also presents an opportunity for the pupils to develop their powers of observation and numeracy. The experiment itself can be extended to enable pupils to develop their ideas about collecting evidence in science and their investigative skills. The resources are all readily available and either cheap or free.