Pleading for the requirements, proposed and elaborated by S. M. Nikolskiĭ and M. K. Potapov, that the introduction of fundamental mathematical concepts in the school mathematics at any level should be motivated by their origination from the practice, and supported by their practical use, the author treats a way in which the concept of variable could be introduced. It is condensed in the form of a series of definitions.

Reviewer:

Vladimir Mićić (Beograd)