Computer simulations of physical events have long been used in school science to support conceptual growth, and sometimes these simulations require students to compare the natural outcomes of physical events with the ‘alternative realities’ that their erroneous prior conceptions lead them to predict (e.g. Hennessy et al., 1995). Typically, however, construction of simulations involves students in complex reasoning, as they have to articulate and then manipulate the parameters upon which their conceptions are based. Psychological research shows that when simulations are merely observed without any requirement to construct or reason, differentiation between natural and non-natural outcomes is possible at an early stage in development, sometimes even in infancy (see Baillargeon, 2002). Using natural and non-natural simulations of object motion, this paper considers whether the ability to differentiate can be harnessed at primary school level for purposes of teaching. The answer was by no means obvious when, on some accounts, the tacit understanding that underpins differentiation involves an entirely different knowledge system from the explicit conceptualization that is the focus of schooling Hogarth, 2001; Plessner & Czenna, 2008).

Two sets of simulations were developed, one set using billiards scenarios to support understanding of horizontal motion, and the other using hot air balloon scenarios to support understanding of object fall. In both sets, the scenarios were embedded in problems, which had the same basic structure.

• Students were invited to predict an outcome, e.g. which pocket on the billiards table a ball will fall into after being struck by the cue ball, will the speed of a ball increase, decrease or remain the same as it falls through air?
• If predictions were correct, students were told that they were correct and invited to observe a simulation of the motion that they had predicted.
• If predictions were incorrect, students were told they were incorrect and invited to observe a simulation of the motion they had predicted plus a simulation of the genuine motion. They were asked to compare the two simulations. 

Baillargeon, R. (2002). The acquisition of physical knowledge in infancy: A summary in eight lessons. In Goswami, U., Blackwell Handbook of Childhood Cognitive Development (pp.47-83). Oxford: Blackwell. Hennessy, S., Twigger, D., Driver, R., O'Shea, T., O'Malley, C. E., Byard, M., Draper, S., Hartley, R., Mohamed, R., & Scanlon, E. (1995). A classroom intervention using a computer-augmented curriculum for mechanics. International Journal of Science Education, 17, 189-206. Hogarth, R. M. (2001). Educating intuition. Chicago, IL: University of Chicago Press. Plessner, H., & Czenna, S. (2008). The benefits of intuition. In H. Plessner, C. Betsch, & T. Betsch (eds.), Intuition in judgement and decision making (pp. 251-265). New York: Lawrence Erlbaum Associates.