Schooling in Australia has become subject to increased processes of data-based governance. This article draws upon the insights of an experienced teacher, 'Meriam', who, having taught more than 34-years over almost a 50-year span, reflected upon the nature of such changes. Utilising theorising in relation to datafication processes and accountability logics, the article elaborates Meriam's efforts to engage productively with increased attention to measuring and monitoring students' performance via various modes of data. This is in the context of increased pressure in the state of Queensland to justify teachers' practices, and to show how their students' learning had shown improvement on these data over short periods of time. In this sense, the article challenges a more post-performative conception of professionalism as Meriam struggled to comprehend how the increased attention to a plethora of data could serve as a useful vehicle to inform teachers' work and learning; this was the case even as she found some benefits in increased attention to her own practice and learning. The article delineates the constraints associated with increased attention to data, and how current managerial and neoliberal policy conditions in schools may contribute to potentially significant and harmful effects for both teacher and student learning.