Are you implying that these two things are somehow possibly related?
It does seem like a confounding factor. Everyone was equally poor compared to everyone else during an unrelated economic depression? i think that would overwhelm any impact of the school closures.
Thanks for the regular reminder that non-programming related threads on Hacker News are filled with completely uninformed comments and are best left unclicked.
Translated: We can't say that "everyone was equally poor" or even that it hit everyone the same. We also can't say that "poor" has 1-1 relationship with educational outcomes (I know it does have an effect). We can also control for things, i.e. my school was closed, yours wasn't 2 blocks way, the Great Depression hit our area the same, I had a worse/better outcome than you did.