It can be even more fundamental than that. I’ve seen people cocking their heads at the existence of multiple windows and programs running simultaneously. As in, “whoa, where’d my assignment go?” after they click on the browser. They’re used to everything running through a single window due to school computers offering everything through the browser. It’s terrifying to me.

they point at excel and say the file is in excel.

the clusterfuck that is Apple's file storage

Out of genuine curiosity: What makes this so bad? I've been in similar teaching situations myself, and find that Finder in column-view is pretty helpful for helping people learn to navigate their file system. One of the first things I do is drop a link to the root folder in their favourites-menu in Finder, then tell them to try to navigate to whatever they need from there, and open it with "Open with". Usually, they start understanding the concept of a file system pretty quickly after that.

Edit: The fuckery that is "iCloud trying to trick you into thinking that files on the cloud are actually stored locally" can go fuck itself though. I've had way too many cases of people suddenly discovering that they have exactly zero files on their computer, because "Desktop" and "Documents" turned out to be links to iCloud...

Use a slide rule and protractor to find the card catalog. Now write your name in cursive to check out a book.

There are YouTube channels with letting the youth try to figure out old tech.

*schools and corpos