My DS5 is a rapid reader- he'll clear 2 or 3 short books a day even though he's only 5, what I am doing with him this summer is letting him chose subjects and buying him factual/scientific based books around those subjects so he can learn at the same time as read- he is a special needs student (dyspraxia, dysgraphia- is being looked at for autistic spectrum issues... but at 5 we're just waited for them to give him a propre diagnosis which could take a while) BUT he is an amazing reader (he reads the news online daily) and has amazing fact recall & memory so we're taking advantage of that fact to keep him busy. At the moment (literally right now) he's sat reading my passporter

as his 2 younger sibs are sleeping, his older one is out with friends.
I find that factual books inspire him to investigate things, ask more questions and generally lead from one subject to the next (example- he read about frogs, which lead him to books about pondlife, which lead him to books about rivers, onto the ocean, we're now reading about whales.... we read about how babies are made and that eventually led to books on the digestive system and eventually food, farming and eco-systems!)
One thing I would say (from experience with my 10 year old daughter) is avoid buying the exact books they may have to read in class next year because if she has already read them she may appear disinterested and her teachers may take that as poor attitude/lack of enthusiasm for school.[/QUOTE]
I've struggled with this too with my soon to be third grader who is gifted and loves reading. However, some books I read-aloud to him a few years ago, were still interesting for him in school this year. When i've read really good kids books at different times in my life (as a kid, as an undergrad, as a teacher, as a grad student, as a parent) like The Giver by Lois Lowry or Charlotte's Web, i've gotten different things out of them and enjoyed them over again.
When doing independent work, i have asked if my child could read something else because he'd read it and already knew the storyline. Not so easy to deal with if its a group or class assignment.
So if a child is a year or more ahead of grade level, it might be not so much of an issue if the book is not fresh in their memory. I would gladly take a list of books from the school /teacher that they will cover, but not had that opportunity/situation yet.
I find it hard to find out ahead of time --exactly what novels will be used in school especially with variances among teachers in same school. Ofcourse if i find out there's one book all of 4th grade will read, i'll try to avoid it --if he hasn't already read it!
I agree nonfiction great way to follow natural interests of kids & get them excited about reading & reading to learn.