The PISA for Development brief series is a set of concise monthly education policy-oriented notes published by the OECD which are designed to describe a specific PISA for Development topic. In this brief, the role of PISA-D to assesses students' skills and knowledge in three cognitive domains--reading, mathematics and science--and collection of data on contextual factors, such as students' well-being, socio-economic status and learning time, through questionnaires distributed to students, teachers and schools is discussed.