On September 8th, the OECD will publish the new PISA results. The results will not be released in December as before, but at the beginning of the school year. And, I must admit, I am quite torn about this. In each PISA cycle, one particular domain takes centre stage. It will be neither mathematics nor reading; this time it will be scientific literacy. Thus, on that Tuesday, there will inevitably be much talk and discussion about how our fifteen-year-olds perform in science. Mathematics and reading will also be assessed, while other topics will emerge in subsequent months in follow-up reports.

However, before this, I believe we should discuss one more issue: what does PISA measure by “scientific literacy”. It turns out that there is much more to it.

If you think that science includes knowing about photosynthesis, electricity, and the difference between a planet and a star, then you only touch upon one aspect of science. Indeed, such knowledge will still be measured in PISA 2025. At the same time, scientific literacy in the OECD context implies that a young person will be able not only to know this kind of stuff but also to explain phenomena.

In their framework, PISA distinguishes three major competencies:

• The first is perhaps the most recognisable: explaining scientific phenomena. For that, you obviously need knowledge. But you must also be able to apply that knowledge, make predictions, use and evaluate models, and formulate hypotheses.
• A second competency concerns critically evaluating scientific research and evidence. For example, students must be able to recognise which question a study answers, think about a suitable research design, and interpret data. They must also be able to assess whether a conclusion actually follows from the evidence collected.
• The third competency stands out as it says a lot about the world in which young people grow up today: seeking, evaluating, and using scientific information to make decisions.

For the last one, you should think of questions such as: Who is actually saying this? Does that person have expertise? How strong is the evidence? Is there a potential conflict of interest? Is it a scientific source or an opinion? And of course, correlation versus causal links, something important for interpreting PISA results too, btw.

You only have to scroll through social media for a moment to understand why the OECD considers this part of scientific literacy today. The challenge is no longer just getting access to information. We are currently flooded with information. Some of it is wrong, misleading, or simply nonsense.

And to assess that information correctly, you need knowledge. So knowledge certainly does not disappear into the background in this new framework.

PISA distinguishes three types of knowledge:

• content knowledge, from, for example, physics, chemistry, biology, and Earth sciences.
• procedural knowledge, knowing how measurement and experimentation work, understanding what variables are, taking uncertainty into account, and being able to think about correlation versus causality.
• epistemic knowledge, or understanding how science arrives at knowledge and why we can trust certain scientific claims more than others.

This last form of knowledge involves a surprising number of things. Think, for example, of: Why do scientists use models? What can models tell us, and what can they not? Why is peer review useful in research? What does uncertainty mean in a measurement? How can data support a hypothesis? And why is a broad scientific consensus a good reason to take something quite seriously, without this meaning that science is infallible?

But PISA 2025 goes a step further. An important new feature is what the OECD calls “Agency in the Anthropocene”. This concerns how young people address climate change, biodiversity, and other major ecological challenges. Here, too, it is partly about knowledge. For example, students must understand how human activities influence Earth’s systems. They must be able to use various sources to consider sustainability.

But here, in my opinion, the framework also becomes clearly more normative. For example, it speaks of respect for different perspectives, hope in seeking solutions to socio-ecological problems, care for other species, social justice, and the willingness to contribute to change.

We could have an interesting discussion about this. When are we still measuring scientific literacy, and when do we start measuring attitudes, citizenship, or certain values? It is a discussion that many others and I have had before about PISA.

We see a similar shift in what PISA calls science identity. This includes, among other things, how students see themselves in relation to science, how confident they are in their scientific skills, whether they find science interesting, and how motivated they are. Environmental awareness and the sense that they themselves can make a difference are also given a place.

This does not mean that on September 8, PISA will suddenly report a single, large mixture of knowledge, attitudes, and climate concern. But it does mean that we need to be careful when we say that young people are “good” or “bad” at science. There is a lot behind such a statement. A PISA score for scientific literacy does not simply mean: how much science do our fifteen-year-olds know?

It is also about what they can do with that knowledge. Whether they can critically assess evidence and information, and whether they understand how scientific knowledge comes about.