Is there something stopping you, or anyone from writing it down and taking notes in class and then reviewing it later as needed? Not just process it in lecture time, but regurgitate it to physical form for later review.
Also, I would definitely constrain this into educational groups, where K-6 are much different from college (post mandatory) education.
It is a skill, but everybody seems to think it will just happen on its own.
Are you really trying to put the genie back in the bottle to the extent of making high schoolers write all their coursework by hand? Or maybe we should bring back the typewriter for distraction-free essay writing...
You make this sound like it is some long-gone practice. I was writing maths by hand as recently as 2020 in university, for my CS-associated maths courses (linear algebra, calculus, physics for computer graphics, etc).
In pre-university essentially all coursework was done by hand, and the national exams are all still handwritten.
...and studies show, inferior for recall:
https://www.scientificamerican.com/article/why-writing-by-ha...