School readiness evaluations are becoming increasingly popular, and their implementation has become compulsory in an increasing number of kindergartens and schools in Hungary. In recent years, Diagnostic System for Evaluating Development (DIFER), developed by Nagy et al. has been used extensively for the diagnostic study of four- to eight-year-old children. The theoretical background for this study was provided by the theory of meaningful learning and concept mapping, the project method, and two domains of DIFER, i.e. the comprehension of relations and experiential reasoning. The aim of the research was to apply the project method with the support of concept mapping. Our target group consisted of school and preschool kindergarten children. Based on the effect size, it is clear that the experiment was successful and a strong effect was observed. As for the future, applying concept maps and involving this technique in everyday life are called for in more domains.