Ever since education moved into schools, instruction has been considered the province of teachers. How does the status of professional judgement change when algorithms enter the classroom? We argue that the knowledge claims around algorithmic management are not a conflict among competing professionals. Nor does it replay the standard conflict between professionals and managerial oversight. Algorithmic management is not simply a different way of managing professional activity but claims to carry out the activities themselves. Here, we examine three public encounters as illustrative of the classification work in which the competing knowledge claims of teachers and engineers are tried out and tested.