Katie is an ordinary fourth-grader -- except for one very extraordinary problem!
Oh, no! Is Mr. G. leaving Cherrydale Elementary? That's what Katie and her friends are worrying about. They can't let him go! He's the best teacher they've ever had! So the kids in 4A come up with a plan to make sure he stays. But when Katie switcheroos into Mr. G., she learns his secret -- and discovers the huge mistake she and her friends have made!