No experience with homeschooling here (no kids 
) but I have some thoughts. Many parents suffer from the fact that each teacher provides its learning material through different channels and formats. Plone is great for organizing content, making it available on different levels to different groups of peoples with different permissions through a unified solution: the Plone UI. Plone clearly has an issue with managing of non-Plone content like files (DOCX, PDF etc). That's why people love cloud storage like Dropbox oder Google Drive which provide a transparent and seamless integration with their desktop and operating system (forget Plone connectivity via WebDAV here). Mix both - Plone and cloud storage can be easily complished using "rclone" and an add-like my xmldirector.connector:
So high-level idea: teacher can throw their content into their favorite cloud storage, Plone with the help of "rclone" could aggregate and federate the various data sources into Plone...
Just as an idea..