How does PISA assess science literacy?

Every three years, in December, it’s PISA time around the world. The education community in participating economies eagerly awaits the latest results from the OECD Programme for International Student Assessment (coming out on 6 December this year) to see how their school systems compare with others across the globe. The most recent round of the assessment, PISA 2015, focused on 15-year-olds’ science literacy, defined as “the ability to engage with science-related issues, and with the ideas of science, as a reflective citizen”. To succeed on the PISA science test, students had to display their mastery of three skills: explaining phenomena scientifically (based on knowledge of scientific facts and ideas), evaluating and designing scientific enquiry, and interpreting data and evidence scientifically. As this definition makes clear, remembering that a free-falling object on Earth has an acceleration of 9.8m/s2, or what the difference between bacteria and viruses is, will not necessarily be rewarded with a high score in PISA (although it might be important to know those facts too). Rather, PISA emphasises that a science-literate person is one who uses that knowledge to navigate through today’s world; and that all of us sometimes need to “think like a scientist” – to weigh evidence and come to a conclusion, and to understand that scientific “truth” may change over time, as new discoveries are made – particularly when we engage with science-related issues. And science-related issues are ubiquitous. Every day, the public is bombarded with new messages based on science – from the advertising claims that a toothpaste kills “99% of bacteria” to the nutritional information on packaged food or the report about the latest Mars mission in the evening news. An understanding of science, and of science-based technology, is necessary not only for those whose careers depend on it directly, but also for any citizen who wishes to make informed decisions related to the many controversial issues under debate today – from more personal concerns, such as maintaining a healthy diet, to local dilemmas, such as how to manage waste in big cities, to more global and far-reaching considerations, such as the costs and benefits of genetically modified crops or how to prevent and mitigate the catastrophic consequences of global warming