The Fourteenth Goldfish by Jennifer Holm

This is a book about science, friendship and life...with a sprinkling of family dynamics.  Eleven year-old Ellie has just entered middle school. She is discovering that everything safe that embodied 5th grade can no longer be counted on - even her best friend Brianna has drifted away to a new group of friends.  

Then...her grandfather (the scientist with two Ph.D's) appears...in the body of a 13 year-old boy...claiming that he has discovered the secret to reverse aging.  And just like that, her grandfather is a student at her middle school! But Ellie doesn't seem to mind - she gets caught up in her grandfather's world of discovery, learning about Jonas Salk, Marie Curie, Louis Pasteur...and a world of science that she had never before appreciated.

This is a fun, easy to read story that celebrates science, exploring, and "believing in the possible." It is full of quirky characters and a story line that moves right along.  Realistic? No...but it doesn't need to be.