Caleb Gattegno (1911-1988) was an educator in many fields, including mathematics, literacy and foreign languages. He could span these disciplines as a teacher because of his insight into how people learn. This was the basis of his ability, demonstrated on many occasions, to teach almost anything to anybody, individually or in large, diverse groups, and whatever the age of the learners. He did this in many languages. Gattegno was a close observer of himself and others, and wrote about teaching, learning and psychology throughout his life. This culminated in his proposals for a Science of Education. He devised techniques and produced materials that make it easier for teachers to help their students learn. Together, the theory and its practical applications show how the actions of teachers in the classroom can always be a response to the learning of each individual student, from moment to moment. In his terms, teaching is then genuinely subordinated to learning. It is easier to understand Gattegno's approach to teaching when one has an understanding of his ideas about how people learn. This book presents the model of human learning that he developed, and shows how it can be applied inside and outside the classroom.