What are the differences among American, German, and Japanese classrooms? If we take as a cue the anecdote told by Stiegler and Hiebert (1999) in their book The Teaching Gap, in a Japanese classroom there are students and there is knowledge and the teacher serves as a mediator between them. In a German classroom there are also knowledge and students, but teachers perceive this knowledge as their property and dispense it to students as they think best. In the American classroom there are teachers and there are students, but the status of knowledge is uncertain.

In this book we are offering a perspective that is different from those mentioned, yet poses the same fundamental question of the relationships among students, teachers, and knowledge. Our perspective is grounded in the theory of Lev Vygotsky (1896–1934), whose ideas turned out to be instrumental in shaping the learning processes in a growing number of classrooms in Russia, Europe, and the United States. At the heart of Vygotsky's theory lies the understanding of human cognition and learning as social and cultural rather than individual phenomena. During his tragically short lifetime Vygotsky developed this central thesis in a variety of areas including the theory of child development and educational psychology. He explored relationships between language and thought, instruction and development, everyday and academic concept formation, and a host of others. For a number of decades his theory inspired only a relatively small group of followers in Russia and Eastern Europe.