Short answer is that a lot of kids aren't studying at all.
In general, Traditional methods have lost favor for new tech based methods.
And New tech is not as good.
Digital texts can be useful for teaching certain foundational skills, but they do not equally develop cognitive patience and slower, deeper processes in the brain that serve comprehension, retention and focus.
www.govtech.com
With math, a lot of the software is set up to be recursive and gamified. The pencil and paper stuff is often "the new math".
Drill and kill is gone.
I asked my FB friends with kids if they were still teaching cursive. Apparently That's been gone for at least 20 years.
While that is happening, fine motor skills are in decline.
Lack of physical activity is a global public health problem causing not only morbidity and premature mortality, but it is also a major economic burden worldwide. One of the cornerstones of a physically active lifestyle is Motor Competence (MC). MC is ...
www.ncbi.nlm.nih.gov
I'm sure it's just a coincidence.
Just like I'm sure that the rise of populism is unrelated to our educational decline. Totally random