Abstract: Based on Mcdemott & Larkin's theory, a hypothesis was made on the representation system in the process of mechanic problem solving. The system was assumed to consist of four stages of representations as students solve a mechanic problem, such as literal, naive, physics and mathematic representation. Furthermore, the system of representation has "dynamic" feature, showing the development of four representations. It is verified that the theoretical hypothesis empirically by employing protocol analysis method. The results from the study showed that subjects always created four representations consecutively in certain order when they solve physics problems. Moreover the time consumed in the literal and naive representation stages is significantly shorter than that in the physics and mathematic representation stages, but it is not significantly different either between the former two stages or between the latter two.

Key words: physics problem solving, representation, protocol analysis