For example, see "school of the air", an Australian rural education program that used to run over radio.

https://en.wikipedia.org/wiki/School_of_the_Air

Australia has long been a world leader in distance education, likely because they had such a large problem, and a head start on solving it.

Our school barely has enough books to cover three classes, let alone the entire grade. Likewise, I've tried calling students on the numbers their parents listed both on the syllabus and on the official enrollment forms have still have sometimes had it unanswered.

Yep. Post service is still working. People have been homeschooling their children long before the internet became ubiquitous.

The kids will just retreat to their study? At a lot of homes, there are much bigger challenges than just internet access.