ABSTRACT
The experiment’s major objective was to determine the subjects’ understanding of various principles concerning length that were embodied in Grize’s axiom system. To this end, 14 tasks instancing those principles as length problems were administered to the children. It was necessary, however, to control the children’s tendency to guess in a problem that they could not solve inferentially. To limit guessing, 11 tasks that in fact were not solvable were randomly intermixed within the 14 solvable tasks. The subjects were warned repeatedly that some of the tasks had no answer, and that when they found such a task, the “best” thing to do was to say that not enough information was provided for the problem’s solution. Explanations for their answers were also required in an attempt to make lucky guesses improbable.
