You've probably already seen the thread on Book recommendations: age 6-8?

From time to ElizabethN updates this post on the recommended book thread, summarizing and categorizing all 8 pages of recommendations. About midway through the post, there is a category described as "Non-fiction(ish): This list includes stories that are technically fiction, but their primary purpose is to teach instead of to tell a story."

Other than that list, for a kid who seems to enjoy reading facts I would recommend National Geographic magazine... (or the kids' version)... while not fiction, the content is rich in information and flows like a story... imparting a sense of grammar which the writing in a technical manual would not. (Caution - preread to determine whether content of each issue is suitable for your child.)

Also any of the DK books or Smithsonian books... while not fiction, they are full of fun facts and useful information... great illustrations, too.

Free online book selection databases include:
- Lexile Find-A-Book,
- Scholastic book wizard,
- Every Good Book (does not include Lexile Level... choose from broad reading level bands: Elementary, Middle School, Secondary/Adult).

Lists of great kids' books:
- American Library Association (ALA) - Association for Library Service to Children (ALSC) - Caldecott Award winners
- ALA - ALSC Newberry Award winners
- ALA - ALSC Notable Children's Books