Play can profoundly influence the growth and structure of the brain. But in the critical years before the age of 5, what kind of play is best and in what surroundings?
Psychobiologist Colwyn Trevarthen explains how recent scientific research might affect the choices people make for their children.
And Dr David Weikart reveals the provocative results of his 28-year study of pre-school education in the USA.
Producer Jonathan Drori