I have a book called "Dogspeak" "from the editors of Pets Part of the Family" I got it for Christmas and haven't really read it yet, but it looks about middle-schoolish.
Also, I thought "The Power of Positive Dog Training" by Pat Miller was a pretty easy read, but maybe more toward the 14-16 age range than 11-14.
What All Good Dogs Should Know: The Sensible Way to Train by Jack Volhard is pretty easy (and even has cartoons) I no longer agree with everything it teaches, but it's generally positive training.
"Clicking with Your Dog" by Peg Tillman (I think) is also very easy to read.
Here's urban puppy's website http://www.urbanpuppy.com
Is that what you were thinking of, Heather?