I could not get to the original study, but the article seems to be cherry-picking data. What was the time-line of the study? Is this a short term or long term e

I could not get to the original study, but the article seems to be cherry-picking data. What was the time-line of the study? Is this a short term or long term effect? Perhaps homework isn't the only thing that counts? Also, what was the availability to broadband/internet access?