The article deals with the problem of development and funkctioning of knowledge in the process of thinking in preschool children. The process involves forms of knowledge significantly differing in the level of maturity. There appear therefore some inner conflicts between them which form one of the driving forces underlying thinking in children. The author provides general characteristic of the structure of the cognitive sphere, as well as peculiarities of its functioning. Some new forms of teaching the preschoolers, based on the above regularities of their thinking are suggested.