Leo Flixtor, a cranky lizard voiced by Adam Sandler, and his turtle companion, Squirtle, observe the lives of a group of fifth-graders from Florida. Leo has been watching children come and go for 74 years and has only one year left to live. He plans to break out of the terrarium and explore the outside world, but instead, he connects with the students and assists them in overcoming their problems while they spend the year with their ornery substitute teacher, Ms. Malkin.