This article examines how teachers at one elementary school made sense of their instructional practice after their school adopted a personalized learning platform for teaching mathematics. Data includes interviews (n = 21) with 12 teachers and administrators as well as recordings of 18 hours of professional learning sessions. The study investigates how teachers' perceptions of their instructional practice shifted as their interactions with students became increasingly mediated by platforms. Findings illuminate how platformization invited digitally mediated surveillance into the classroom and how this surveillance impacted teachers' perceptions of their relationships with students and with content. The authors offer a framework of platformized instruction to guide research on teaching the digital era.