TEACHING ABOUT ROLLING MOTION: EXPLORING THE EFFECTIVENESS OF AN EXTREME CASE REASONING APPROACH

Teaching and learning about rolling motion often requires combining of concepts of translational and rotational motion. Consequently, this relatively complex topic provides a natural context for synthesis of conceptual knowledge from various areas of mechanics. However, earlier research consistently shows that most science and engineering students struggle with developing a satisfactory understanding of rolling motion (De Ambrosis, Malgieri, Mascheretti, & Onorato, 2015; Duman, Demirci, & Sekercioglu, 2015; Lopez, 2003; Mashood & Singh, 2012; Rimoldini & Singh, 2005). Rimoldini and Singh (2005) found that students in introductory and physics junior courses very often do not understand the role of friction force in rolling motion, as well as the distribution of linear velocities across a rolling wheel. In their research none of the 16 interviewed students was able to explain the velocities of the points at top and bottom of the wheel, relative to the ground. It seems that for these students it was hard to understand that, in some instant, a certain point of a moving object can be at rest if we know that the corresponding object as a whole is continually moving (Hasović, Mešić, & Erceg, 2017). According to Lopez (2003) this difficulty could be at least partly associated with the fact that many students do not understand the concept of relative velocity. In addition, by overgeneralizing their experience with translational motion, students often come to the wrong conclusion that acting of frictional forces always is associated with losses of mechanical energy. Being aware of the many difficulties that students have with developing understanding about rolling motion, Rimoldini and Singh (2005) called for designing a conceptual approach to teaching this topic. A possible method for identifying an approach that overcomes the limits of human intuition would be to refer to corresponding excerpts from history of physics. Examples from history of physics show that, in order to discover deeper truths about the physical reality, scientists often had to resort to using analogical and extreme case reasoning (Halloun, 2004; Nersessian, 2008). Stephens and Clement (2007) consider that “an analogy has been proposed Andrej Vidak University of Zagreb, Croatia Nataša Erceg University of Rijeka, Croatia Elvedin Hasović, Senad Odžak, Vanes Mešić University of Sarajevo, Bosnia and Herzegovina Abstract. Earlier research has shown that students have tremendous difficulties with understanding certain aspects of rolling without slipping, such as the zero-velocity at the contact point and plausibility of application of the law of conservation of mechanical energy despite action of the friction force. The aim of this research was to explore whether using analogies and reasoning about extreme cases can facilitate conceptualization of the above-mentioned phenomena. A pre-test – post-test quasi-experiment has been conducted, with 93 students in the control group (CG) and 91 students in the experimental group (EG). Whereas control group students received conventional teaching, in the experimental group rolling of a cylinder has been considered as a special case of a tumbling prism for which the number of prism surfaces tended to infinity. The results of analysis of covariance showed that students from the experimental group significantly outperformed their peers from the control group on the Rolling Motion Concept Test (RMCT). Between-group differences were greater on test items that required higher level of cognitive transfer. This research suggests that using analogies and extreme case reasoning can facilitate comprehension of certain seemingly counterintuitive aspects of rolling motion.