PISA iProgramme for International Student Assessment) is a large-scale international survey that assesses the knowledge and skills of 15-year-olds. The survey was first conducted in 2000 and is repeated every three years. Each cycle examines the same three cognitive domains: reading literacy, mathematical literacy and scientific literacy. The focus is always on functional skills and knowledge that enable people to function actively in society. Based on the PISA results, Flemish education policy can be advised and optimised.