One possible way of examining parents’ mediation of formal thinking has been presented. The specific goal was to construct a scale which represents specific means of parents’ mediation that appear in their everyday communication with children. Piaget’s theory i.e. main characteristics of formal operations and concepts from Vygotsky’s paradigm, especially mediation means concept, served as theoretical background for scale constructing. The similarities between final stages of cognitive development within these two approaches have been analyzed. The research was conducted in which Crombach’s alpha was examined as an indicator of scale quality as well as correlation between children’s answers on the scale and their achievement on formal operations test. The most relevant aspects of parents’ mediation were extracted and analyzed.