Stephen Koch has an interesting discussion of facts vs. truth in his book Writer's Workshop: A Guide to the Craft of Fiction. (I'm loving this book.) He says that whether you're writing fiction or nonfiction, facts alone don't make it. You have to get "possession" of the facts. Internalize them, find their inner truth. It doesn't matter where the "facts" came from, whether they came from they came from reality or your imagination (as in making up a character). John Keats said it this way, "A fact is not a truth until you love it."
I can totally relate to this in writing biographies for children. It wasn't the facts, it was the truth that I found in them, that made middle schoolers tear up when I read aloud Dian Fossey's biography from Women of the Golden State.
Thanks to the Alan Shawn Feinstein Middle School for inviting me to take part in their readathon.