Let's say you're mentoring an author with a spy thriller novel. Digging through your mental backlog and telling them OK, you should read this Tom Clancy. And that LeCarré. Oh, yes, and that Forsyth and maybe....ummmm...what else...., simply because YOU have read them and they are something like what your author is writing, is not only stupid, it's time-wasting. 

That's homework. Forget it. 

Assigning homework only brings your author's knowledge up to your own. Nothing more. That's not progression, that's knowledge parity. YOU are the one with the map and the knowledge. The author is writing. Leave them to write. 

If you feel there is a book, a fact, a picture... whatever...that your author really and truly needs to read, know or see to be able to progress with their piece, then YOU find it, YOU type it out, YOU send it to them. Don't make them do anything but think and write. You are the provider of the knowledge, and the tips. You are the navigator. YOU do the homework.

Some authors like doing their own research. Wonderful. Some are lazy and like junk food and the couch. Wonderful. No homework.

What IS doing mentor homework, then?

It's applying your knowledge of other things to help your author progress.

 Are they trying to describe a setting that rings a bell in the back of your head? Look for a picture of it online and see if that's what they are getting at. 

Do you know of a mythological story that is similar in theme to a current plot knot your author is trying to unravel? Tell them the story, or find a short version and sent them the link.

 Have you seen a painting, or a video that has something of interest or relevance in it? Find it, send the link.  

Talk in depth about what you find with your author, and help them apply it to their current project. 

You are the knowledgable one. You do the homework.