You know when your kid hands you a book and asks, “Can I read this?” and you have no idea what the book is about? You flip through it, hoping to find an age-range or anything that will tell you if the content is right for your child. Yeah, that’s where I was one day when my (then) 8 year-old came staggering toward me with a pile of books taller than she was—books I knew nothing about. Knowing how sensitive she is to some scary stuff, I just didn’t know if she should read them. And she was reading them faster then I was. I got online to find a resource for parents that would give me the scoop on children’s books. Not just a Cliff Notes description of the synopsis or a review, but one that would warn me that the Junie B. Jones books use the word “stupid” a lot. They...