On the issue of substantive diagnosis of theoretical thinking of children in developmental learning

Modern practice of education, based on the idea of ​ ​ the system of D.B. Elkonin - V.V. Davydov, is in dire need of diagnosing the development of theoretical thinking of students in the process of mastering specific disciplines. There are many methods aimed at studying theoretical thinking, but the difficulty is that there is no connection between the methods and the content of the educational activity itself. The author cites possible tasks of subject diagnostics of theoretical thinking of younger students on the material of the topic of adding multi-valued numbers with the transition through the category. Preliminary studies have shown that these kinds of tasks may well be used to substantively diagnose the theoretical thinking of students.