Patron walks into a library...

...and asks,

What resources do you have to assist with my child's reading comprehension? I'm specifically looking for quizzes for the books s/he's reading to test vocabulary, etc. His school has quizzes...

 First I checked out the Accelerated Reading database. There are quizzes, but AR locks access to them at the public library level. After brainstorming with the Children's Librarian I've come up with the following (free) resources:

• Sylvan Learning Center has the cool Book Adventure site. It is free to register (I'd be on the lookout for email ads for their other products) and there are ~ 8,000 books that have quizzes. Discovery is a bit of a hassle, but you can select by grade and reading level and even choose subjects to narrow the search from within fiction and non-fiction.
• Look at the publisher's website for a given book to see if there are any quizzes or book group discussion questions that are prepared to supplement the reading, such as Harper Collins
• Look at Homeschooling Resources to see if there are any lesson plans pre-made for books. Sites such as EdHelper may have been prepped for homeschoolers. (Note, this site requires registration. I have not verified if it is free.)
• Check out the Adventure Reading Packs at Reading Rockets (this is a pretty cool site!) And their companion site Start with a Book!

Finally there's this tried and true, if perhaps time intensive, method: Read the book with your child!!! And ask him/her questions about the book. You know, have a conversation!!! If reading it is too difficult, I'd recommend getting the book on audio and listening to it in the car together. But I'm not going to leave you dear parent without book resources for the types of quizzes or activities you could create. If you, as the parent, need ideas try these:

• Teaching the Classics in the Inclusive Classroom: Reader Response Activities to Engage All Learners by Katherine McKnight.
• Texts and Lessons for Teaching Literature: with 65 fresh mentor texts from Dave Eggers, Nikki Giovanni, Pat Conroy, Jesus Colon, Tim O'Brien, Judith Ortiz Cofer, and many more
•  The DVD Reading for children. Reading Comprehension by Schlessinger, Andrew. Schlessinger Media. First Light Pictures, Inc. (I haven't seen this, so I haven't vetted it yet.)
• The Reading for every child comprehension, grades K-5. (At my system, this series is available as downloadable books.) The kindergarten workbook is perhaps for kids that have already made it through kindergarten and I would definitely say that the parent needs to be involved in guiding the child's use of the activities.

I realize that I'm starting to go down the rabbit hole here. And the original inquiry was for pre-existing quizzes for children's books. The short answer is, no, we don't. The long answer, well, see above.