The articlc deals with the possibilities available to quantitative diagnostics of prcconccpts and the ways of its evaluation. For the purposes of quantitative diagnostics of pre-conccpts, the following concepts were chosen: drugs, energy, burning, density, poisons, acids, plastics, radioactivity, lime, air. Their prc-concepts were diagnosed at the level of the 3rd, 5,h, 7,h and 9‘“ Basic School years. The cognitive dimension of prc-concepts was diagnosed by a cognitive test, the relational and meaning-related level of the affective dimension of pre-concepts was diagnosed using scales and structuring of the pre-concepts according to schemes devised in advance. The article equally discusses the possibilities of evaluating and representing the data obtained and tests the prerequisites related to the change of individual descriptive categories of pre-conccpts in the course of goal-directed school education.