Who would you say suffered the most from the COVID school closures? The obvious answer would be: students from the most disadvantaged families. And that’s true… but only partly. A new international study based on PISA data shows that the answer depends heavily on the country where students went to school during the pandemic.

In advanced economies, average learning loss remained relatively limited. At the same time, however, the gap between advantaged and disadvantaged students widened considerably. Children from more privileged backgrounds were, on average, more likely to benefit from interactive online lessons, digital learning materials, and a stable learning environment at home during the school closures. For more vulnerable students, this was much less common. The result was that existing inequalities frequently became larger.

In less affluent countries, the picture looked very different, according to the analyses by Michele Romanello and her colleagues. Average learning losses were often greater, but socioeconomic gaps increased much less. This was not because disadvantaged students performed better, but because high-quality remote learning was only available to a limited extent for almost everyone. As a result, a much larger share of students lost ground, regardless of their socioeconomic background.

That is perhaps the study’s most important conclusion. School closures did not affect every education system in the same way. In wealthier countries, they primarily increased educational inequality. In less affluent countries, they mainly resulted in widespread learning loss.

How do the researchers explain this difference? According to them, much depends on how remote learning was organised. Students who had access to live online lessons and well-structured digital learning materials generally performed better than those who mainly relied on television, radio, or messages via platforms such as WhatsApp. Technology itself was not the solution; the quality and level of interaction in remote learning made the difference.

This all sounds fairly plausible. Still, I think this final part of the argument deserves some caution. The researchers combine PISA data from 2018 and 2022 with information on school closures and remote learning. That allows them to identify strong associations, but as I’ve written many times before, PISA data cannot establish hard cause-and-effect relationships. The authors themselves also acknowledge that schools offering better remote learning may simply have been better organised long before the pandemic. No shit, Sherlock.

That said, the study adds an important nuance to the debate. The real question is not only how much learning loss COVID caused, but also who bore the greatest burden. And the answer turns out to depend on the context. In wealthier countries, disadvantaged students paid the highest price. In less affluent countries, almost everyone ended up paying part of the bill.