Instability in students' use of intuitive and Newtonian models to predict motion: the critical effect of the parameters involved

Abstract

This study reports how children switch from intuitive to scientific models of explanation of motion when the numerical conditions in the presented problem are changed. Previous studies have suggested that student knowledge of mechanics may be compartmentalized: their everyday intuition serves in everyday contexts and their scientific model is activated, if ever, in academic contexts. In this study we investigate a case where significant numbers of students appear to draw on different models of motion in what is essentially the same, academic context, i.e. the prediction of the motion of a block on a smooth surface under the action of horizontal forces. Many students exhibit combinations of Aristotelian-like intuitions and Newtonian conceptions depending on the magnitudes of the quantities involved. The students' experience of being taught Newtonian theory in mathematics and physics has small but significant effects on the explanations they offer. The notion of anchoring and bridging is re-examined as a teaching strategy in such situtions.