Many students understandably do not want to pay for shared hosting to post web design assignments online, but posting assignments online is far preferable to trying to send zipped up sites back and forth as changes are made. If the site is online, the student can simply make their changes and then the instructor and class can just revisit the website.
It can be tough to evaluate the validity of the many online resources available for beginning web designers. For example, many professional designers take issue with some of the older content on https://w3schools.com, which I somewhat agree with. But let's face it, w3schools can be a good quick online reference.