Let her run through the library shelves a couple times a week. That's what I enjoyed most at 13--just having an hour or so to go along all the shelves and pull out whatever I wanted, which was most always an odd collection. There are librarians there who could guide her if she wanted to ask--I never did--but there's some great power in knowing you can check out as many books as you like on as many varied subjects as you want and there is no rule that states that you must read every single page of everything you check out.