Many scientists have been fascinated by how the brain works, but much of what is known about the brain has been discovered within the last twenty years. In this article, the author explores how thinking and using one's mind are essential to understanding. She contends that children need to be in control of their learning; the adult's role is to provide the resources and the challenges. These should be as real as possible and be motivating as well as fun. All activities should provide a range of opportunities to focus on different senses, so that children are not just reacting to what they see but are active in making links between all their senses and their prior knowledge. The brain requires "challenge" as it runs a powerful all-purpose programme called "learning". (Contains 3 figures.)