The gender gap in reading is huge. And it's biggest in Finland, home to students who are internationally renowned for performing well on standardized tests, as this chart from the Brookings Institution shows:
Girls in Finland are so good at reading that they are carrying a chunk of the nation's academic reputation entirely on their shoulders. Finnish boys aren't standouts in reading at all — their reading scores on the Programme for International Student Assessment are no better than average. Boys in Finland read about as well as boys in the US. Whatever works so well in Finnish schools, in other words, might really only work for girls.
But Finland is just an extreme example of an international trend: for decades, around the world, in every developed country, girls are much better at reading than boys are — and no one knows why.
Study author Tom Loveless uses the PISA data to test a few theories, and comes up empty. When boys' enjoyment of reading goes up, their test scores don't always, which suggests that the problem isn't that girls just like to read more. The gap between girls' and boys' scores has shrunk in the US over the past 40 years, which suggests it's not a developmental or biological issue — "biology doesn't change that fast," Loveless writes. And the problem eventually goes away: by their 20s and 30s, adults in both countries read at similar levels.