Children have a spontaneous interest in the world around them - whether the workings of the earth, sun, and stars, the nature of number, time and space, or the functioning of the body. Yet what is there in children's minds that is the key to their knowledge? This book examines what children can and do know, based on extensive studies from a range of different cultures. Topics include 'theory of mind' - the knowledge that others may have beliefs that differ from one's own and from reality, astronomy and geography, food, health and hygiene, processes of life and death, number and arithmetic, as well as autism and brain research on language and attention. Since what children say and do may not really reflect the depth of their knowledge of the world around them, our goal should be to discover new methods to accurately test children's knowledge, instead of trying to understand the range of failing answers they might give on the many tests that have been devised to determine what they know. Contrary to earlier studies, it is now established that in many areas considerable knowledge is within the grasp of young children with benefits for their later development. For example, although certain number concepts - in particular, fractions, proportions, and infinity - can be difficult to grasp, children generally do not need to undergo a fundamental change in their thinking and reasoning to master these. What the author of this book proposes is that children often display a capacity for understanding that we simply overlook. Written by a reknowned developmental psychologist, this book presents a fascinating exploration of children minds, and how we can better understand them.