This article overviews the theoretical and applied works of the psychologist and pedagogue Leonid Zankov. Zankov's model of teaching is based on Vygotsky's theory that appropriate teaching methods stimulate cognitive development, whose core notion is the Zone of Proximal Development. This educational psychology research was verified by large scale pedagogical experiments conducted in 1970s at public schools in Russia. Over several decades L.V. Zankov with co-workers and followers created the comprehensive system of developmental education for elementary school. The Zankov education system is used now at public schools in Russia. Its main principles and properties are described.