In recent years there has been a global call for more scientific knowledge about education as a basis of governance. This means that exact descriptions of the reality of schooling should inform decisions about what works in education. In this article, evaluation and testing are analysed as cartography, the art of mapping educational spaces, which both creates and confuses our sense of educational reality. By using elements from cultural studies of cartography as well as sociology and the philosophy of science, this article claims that the analogy of cartography and evaluation can open novel vistas for contemplating the relationship between the world of education and its scientific representation. As a case in point, the article uses the construction of Finnish comprehensive basic school reform and the evaluation system pertaining to it. The analysis shows how evaluation as the mapping of the reality of education brings distant objects near, onto a homogeneous, stable plane. It also makes certain things visible while leaving others out of sight. Furthermore, evaluation as cartography is not only passive representation; it actually creates new spaces. In this way, evaluation practices can profoundly affect how we think and act upon schooling. (Contains 2 notes and 1 figure.)