The means of draught construction shows itself in the capacity of cognitive activity's variety, forming theoretical thinking in schoolchildren. Carrying out practical actions with the help of planks, the schoolchildren produced the models of geometrical figures and then they reproduced the results of practical actions in materialized form (as a draught). All this imparts certain trend to demonstration process because the draught serves as a source of geometrical notions (theorem's and problems') emergence. On the basis of making and constructing of two equal traingles with common base the formation of some geometrical notions, theorems and problems took place.