Abstract
The article introduces the main concepts of constructivist theory (prekoncept, miskoncept) in the context of what are called pre-school children, preoperative stage (according to J. Piaget) are able to perceive.
It reminded didactic principle of proportionality. It is a small research probe - the search for answers to the question "Tell the children that Santa Claus does not wear gifts?", "When?" and "How".