Graphs are an important interdisciplinary and everyday tool for visualizing and interpreting information and communication processes and, thus, an essential part of 21st Century Skills. In particular, linear functions are a fundamental component of school and university education, but students often have difficulties interpreting this type of function, in mathematics as well as in physics especially in kinematics. This paper presents first results of an eye-tracking study, which compares learners' visual attention during the interpretation of linear graphs in mathematical and physical contexts.