This article explores the cultural practice of observation in teacher education, focusing on how teachers "learn to see" the differences between students. Conceptualizing "the visual" as a curricular problem that produces certain knowledge as in/valuable, I historicize the practice of scientific observation as embodying anticipatory reasoning, which directs teachers to see, name, and categorize the differences in the present in relation to the normative future. The analysis highlights the double gesture of observation; whereas teachers understand seeing diversity as a precondition to providing pedagogical and curricular supports for all students, this practice actually maintains the boundaries that demarcate human differences. The findings provide insights into evidence-based education today. Compared to the teachers at the turn of the twentieth century who contributed to visualizing racial differences, today's evidence-based reforms prepare teachers to reduce the achievement gap that is associated with students' racial, ethnic, and linguistic diversity. Despite this historical change towards more equitable education, teachers continue to contribute to reifying the racialized social ordering by failing to question how the white-centric gaze of deviancy structures the racial, ethnic, and linguistic diversity in the education system. I suggest that studies of diversity in education should consider visual politics and that teacher education programs should promote cultural and historical sensibility to prepare teachers to challenge the pre-established curricular discourse and systemic racism.