A Chapter Book?

Recently, a friend of mine asked me if the book I was writing was a "chapter book". I replied "yes", but the more I thought about it, the more I began to doubt my answer. In a previous post,  I relayed how I came to the conclusion that "Middle-grade" was the appropriate category for my book. But is MG a subset of  a broad "Chapter Book" category or is "Chapter Book" a category unto itself? An initial Internet search only brought more confusion. The New York Times Best Sellers list has a division called "Chapter Books" which includes everything from Lego books (ages 7 and up) to Rick Riordan's Percy Jackson series (which is considered by many to be Young Adult in the tradition of Harry Potter). Finally, under a Children's Fiction genre definition at findmeanauthor.com, I found definitions I was satisfied with:

Chapter books - "For ages 7-10, Chapter books are transitional books that help children move from early readers to full novels. Most chapter books deal with contemporary situations that are familiar to the readers, and are often humorous books."

Middle-Grade Novels - "This is the golden age of reading for many children, ages 8-12. A novel, unlike the picture book, relies entirely on text to tell the story. Kids get hooked on characters at this age. Fiction genres range from contemporary to historical to science fiction/fantasy."

Spacemouse 9 fits better in the MG Novel category. So, the next time someone asks me if I am writing a chapter book I will say "No, I am writing a Middle-grade novel". ;)