Although graphs are used in both mathematics and science, there are disciplinary differences in the types of tasks, the terminology and the purpose for graphing. This can make it difficult for students to transfer their learning from one subject to the other. By examining the differences in how graphs are used, and the reasons for these differences, we can better understand the issues faced by students in applying graphing skills in both mathematics and science. There is, therefore, a need for science teachers to take realistic account of what students learn about graphing in mathematics.