Educational data can have important and useful functions at a number of levels; governing through data can include monitoring, highlighting and challenging disadvantage, inequality and social injustice throughout the education system. Data systems can allow us to connect different forms of information, and 'democratise decision-making processes' through increased transparency and making 'elite actors more 'accountable' for their actions'. Datafication has intensified processes of performativity, creating a hyper-performative atmosphere where everything must be quantified and accounted for. This chapter focuses mainly on the operation of data within schools, on their impact on practice and pedagogy, subjectivities and strategic responses, but with an awareness that the 'statistical journey' of the data in question continues through onto government comparative websites, such as RAISEonline, that are central to inspection outcomes. Teaching, learning and understanding are essentially political and ethical relationships imbued with power; assessments such as Baseline draw children out of their complex, diverse and distinct cultural backgrounds through a universal 'technique of normalisation'.