Concept maps have a variety of use in various spheres of education. They externalise misconceptions and serve as a tool for introspection. Concept mapping students are compelled to build bridges between their prior knowledge and new knowledge. The prior knowledge of a group of sixty Year Eleven Physics students was measured to divide them into two groups, namely, students with adequate prior knowledge and students without adequate prior knowledge. The author compared the achievement of the students who adopted the technique of concept mapping as a study tool with the ones who did not and found no difference between the two groups irrespective of the adequacy/inadequacy of their prior knowledge. Since the Achievement Test consisted of questions which involved numerical problem solving and graphical interpretation, it might be concluded that although the technique of concept mapping might modify cognitive structure, there is no evidence in this study that suggests an improvement in problem solving skills in Physics. Furthermore, the author used the available literature to examine the information processing theory of problem solving, namely, how prior knowledge is used during problem solving.