Could it be an interest thing? DD loves to read and while I do have her narrate to me some, I have found that if she is really into the book she talks about it without any prompting, to the point that she will come running to me to tell me all about it. I have found this with the Roald Dahl books and the How to Train Your Dragon books and the Narnia series especially. She will go on and on and excitedly tell me everything even when she is interrupting me in the middle of something else. On the other hand, if she's not into it,say a book that I have assigned for school that she is okay with but not in love with, she totally comprehends it, but it takes lots of questions and prompting to find out what happens. So maybe he just isn't that into the books that they are asking him to read, either not his thing or way to below his level, and so having to talk about it is frankly boring. Just my thoughts. Good luck.
