In our study, we looked for an answer to the research question “How prospective teachers comprehend the concept of a plane angle and what kind of variation there is between the conceptions? The study shows that the prospective teachers interpret the concept “plane angle” which in principle is familiar to everybody in many different ways. In this paper, we categorise eight interpretations of a different type, appearing in the future teachers' ideas. We also show some examples of the fact that individuals can use different concept images of a plane angle when performing the tasks of different types even in the same test.