This study aimed to analyze the effects of computer-assisted teaching (CAT) on the graphing skills (understanding, evaluating, and drawing) of student teachers of science and their attitudes towards using graphics. Experimental method was used in the study. The Scale of Attitudes towards Using Graphics and the Graphic Drawing, Understanding and Evaluating Test were used in the study together with worksheets. Six students from the treatment group were interviewed following the application. Forty students studying at Year 1 of Hacettepe University Department of Secondary Science and Mathematics Education participated in the study. The treatment group received teaching through computer-assisted teaching applications within the constructivist approach, while the control group was taught through the traditional method. In the computer-assisted teaching applications, a tool that was developed specifically for this application was used. It was observed that computer-assisted teaching was more effective on changing the attitudes of student teachers towards using graphics on the positive direction as well as improving their graphing skills.