This book is the result of a unique experience: a research mathematician teaching in an elementary school. It tells about a fascinating discovery made by the author — that elementary mathematics has a lot of depth and beauty, and that the secret to its teaching is in understanding its deep points.The first part of the book discusses the nature of mathematics and its beauty. The second part tells about the teaching principles the author distilled from his experience. The third part is an excursion through the arithmetic studied in elementary school, accompanied by personal stories, historical anecdotes and teaching suggestions. The appendix relates the fascinating story of modern day politics of mathematical education.The book was a bestseller in Israel, and has been translated into many languages. The extraordinary combination of mathematical and didactic insights makes it an essential guide for parents and teachers alike.