PISA is the world's biggest international education survey, involving schools and students in over 60 countries.
It assesses the knowledge and skills of 15-year-olds in maths, reading and science and was developed jointly by member countries of the OECD (Organisation for Economic Co-operation and Development).
The PISA survey has a three year cycle, focusing in turn on maths, reading and science. The focus of PISA 2012 is on maths, with some questions assessing reading and science. Students in England will also take part in a computer-based assesssment of problem solving.
Findings from the survey will inform education policy in the UK and other countries, and will be used to improve teaching and learning in maths, science and reading for students around the world.
In the UK, the PISA survey is run by the National Foundation for Educational Research (NFER).