Vygotsky's doctrine of scientific concepts as the content of school instruction is a direct elaboration of his general theoretical view of mediated learning as the major determinant of human development (see Kozulin, this volume). According to Vygotsky (1978, 1981, 1986), all specifically human mental processes (so-called higher mental processes) are mediated by psychological tools such as language, signs, and symbols. These tools are invented by human society, and they are acquired by children in the course of interpersonal communication with adults and more experienced peers. Having been acquired and internalized by children, these tools then function as mediators of the children's high mental processes.

Vygotsky viewed school instruction as the major avenue for mediated learning and, therefore, as the major contributor to children's development during the period of middle childhood. He emphasized, however, that such a development-generating effect of instruction would take place only if the process of instruction were organized in the proper way: “The only good kind of instruction is that which marches ahead of development and leads it; it must be aimed not so much at the ripe as at the ripening functions” (Vygotsky, 1986, p. 188). According to Vygotsky (1978, 1986), the major reason for the development-generating effect of properly organized school instruction relates to students' acquisition of “scientific concepts,” which can be contrasted with “spontaneous concepts” of preschoolers.

Spontaneous concepts are the result of generalization of everyday personal experience in the absence of systematic instruction. Therefore, such concepts are unsystematic, not conscious, and often wrong.