Abstract Continuing with the didactical analysis of main topics of
school arithmetic, first we cover the technique of using place holders as an
indispensable device for realization of aims and objectives present in the
contemporary process of learning and teaching arithmetic. To ensure the
enforcement of correct responses and clear goals of calculation, we insist
on the function of these graphical signs as being holders of blank spaces
(and it means that a numerical value should never be assigned to such
signs).
Though an ongoing idea of ``early algebra'' has not yet got its clear
contours, it puts forward a more extensive use of numerical expressions in
the elaboration of arithmetical topics. In this frame, we consider
meaning-based equating of different numerical expressions and establishing
of the main rules of arithmetic on that same base. The manner of expressing
these rules is of three kinds: procedural (example by example), rhetoric (in
words) and symbolic (using letters in the role of variables). The order in
which these three manners have just been mentioned is the natural one to be
followed in school practice. The procedural manner is also one which is
inevitably connected with the use of place holder technique and we treat it
here with scrupulous attention to detail.
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