In this contribution to the Platform Studies in Education symposium, Luci Pangrazio, Amy Stornaiuolo, T. Philip Nichols, Antero Garcia, and Thomas M. Philip explore how digital platforms can be used to build knowledge and understanding of datafication processes among teachers and students. The essay responds to the turn toward data-driven teaching and learning in education and argues that digital data is not only generated through national-, state-, and classroom-level assessments but also produced through the platform technologies that increasingly support all kinds of school operations. While much has been written about the promise of such technologies for schools, less is known about the role digital platforms play in constituting this data and how the platforms can be critically engaged to build knowledge and understanding of datafication processes in classrooms. This article explores these dynamics through three vignettes that investigate platforms as an interface for teaching and learning about data. In doing so, the essay speaks back to three interrelated properties of datafication--reduction, abstraction, and individualization-- in ways that can be made visible for analysis, critique, and resistance in schools.