Clementine's Letter by Sara Pennypacker

Clementine is getting along much better in 3rd grade because her teacher has discovered some personal "rules" to help her know when to listen, when she is doing well, etc. But she falls apart when a sub takes the teacher's place - because he has been nominated for a teaching experience in Egypt. Clementine is certain her negative letter of recommendation will ensure her teacher's return to the 3rd grade class! (This is the third book in the "Clementine" series!)

Fairy Tale Detectives by Michael Buckley

Samantha and Daphne think they are orphans until they are claimed by Grandmother Grimm. Turns out they are related to Jacob and Wilhelm Grimm, the famous fairy tale collectors, and are needed to help take care of some fairy tale problems. Many years ago the magical creatures in fairy tales (called Everafters) were sent to one town, Ferryport, to live separately from humans. Now, one giant is running loose destroying the town. Samantha and Daphne help solve this problem and learn about their own family history!