The use of graphical representation as reasoning tool in transferring content knowledge through source processing was explored in this study. Studies established that students competency in graphical representation is essential part of learning. The study investigated the parameters under which beginning physics students use graphs as a tool in mediating a content area (mathematics) into another (physics). One hundred fifty-six students were given kinematics problems. One set of problems required the active use of graphical representations, while the other set of problem does not require active construction of graph, this referred to as passive graphical representation. To control for transfer effect of established knowledge, pure text problems were also administered. ANOVA was used to determine if there is a significant difference in the mean scores of the students in the three activities. Furthermore, students were given achievement tests. The scores from these two tests were correlated. In general, the results showed that active representation of graph is powerful tool in problem solving skills of students. I addition to that, the finding showed that the used of graph in the instructions improve students' competency in graphical representation.