The global neoliberal context and the emergence of new forms of 'governance by numbers' is now recognized as a ubiquitous educational phenomenon. In this context, large-scale assessments such as are used to justify marketised ideals of education that rely on comparison by numbers. In Australia, one of the key arguments for large scale standardised testing is that it increases transparency and provides parents and policy makers with important data; and that it ultimately drives student achievement. Although standardised assessments purport to improve transparency, limited attention is given to how the quantification of education changes the nature of teachers' work. This institutional ethnographic study investigated how student achievement data on standardised tests served to reorient the work of teachers in six Australian schools. As educators increased their efforts to 'improve their data' these efforts limited alternative curriculum and pedagogic possibilities, such as fostering student creativity in the teaching of writing.