There were some studies that showed how length of closure affected academic impact: https://www.sciencedirect.com/science/article/pii/S095947522...

A year of half-assed online work could have a pretty big impact. Many schools weren’t well prepared to run classes online.

Thanks, I haven't seen this study before. In table 2, it seems like the biggest impacts were on people that didn't speak the test language well, and strangely girls. The duration of school closure was negative, but not as negative as those other factors. I am having trouble explaining that. The non-native speaker element seems quite logical, but the large difference across genders and the relative insensitivity to closure duration is strange.

I agree, perhaps the gender effect has something to do with how girls are socialized and how that affects their learning process.

I also saw a separate Japanese study that showed more lasting effects in lower income families, with scores mostly bouncing back in others. But that’s Japan, hard to generalize with how they do schooling and out-of-school study.