It is well-known that digital learning materials influence the classroom curriculum and didactics. At the same time, few studies examine the role of the data visualizations offered by digital learning materials. Data visualizations signpost the emergence of students as data subjects who can be observed and compared on a computer screen. They thus shape teachers' socio-technical ways of seeing student learning and are likely to influence student assessments. Drawing inspiration from Science and Technology Studies (STS), this paper advances an analytical framework for eliciting the politics of data visualizations, focusing on automation, agencies, and aesthetics. The framework is exemplified through a case study of a popular Danish digital mathematics platform. In a concluding discussion, the paper considers the importance of addressing unsettled and ethical questions about the role of automated digital systems in teachers' knowledge practices.