I've recently come across THE BUDDY FILES, by Dori Hillestad Butler. Buddy is a who lives with a boy named Conor, and Conor's mom, an elementary school principal. Buddy is a trained therapy dog, but he also fancies himself a dog detective. In each book, he is trying to solve a different mystery. Periodically throughout each book, he stops to make a list of the clues he has uncovered, and the questions he is still trying to answer. (An aise: That little teacher voice in me kept saying, "These would be great for helping beginning chapter book readers work on their thinking strategies).
BOOK ONE: THE CASE OF THE LOST BOY
Buddy has always lived with Kayla and her parents, but then the family moves, and Buddy is left at the pound. Soon he is adopted by Connor, and his mom, a school principal. But then, one day when they are on a walk, Conor disappears. It’s Buddy’s job to find him!
BOOK TWO: THE CASE OF THE MIXED-UP MUTTS
Buddy is at obedience school when he meets Jazzy and Muffin, two pugs that got mixed up at a dog park. Buddy and his friend , Mouse, help the two dogs get back to the right family.
BOOK THREE: THE CASE OF THE MISSING FAMILY- Buddy loves Conor and his mom, but he wonders what happened to his first owner, Kayla, and her parents. When he has the chance to travel to Kayla’s new town, he jumps right into the back of a moving van. Will he find his old friend?
BOOK FIVE: THE CASE OF THE LIBRARY MONSTER- Buddy is in the library one day when he encounters an unusual blue-tongued monster. Who is the monster? And what is it doing in Buddy's school?