A.J. and his friends get a Personal Digital Assistant named Miss Porter as a substitute teacher, who can order pizza and tell endless jokes, but grows power-hungry when her system is changed and tries to take over Ella Mentary School.

A.J. and his friends think that Ms. Todd is the strangest substitute teacher in the world, and they decide to investigate her.

When her substitute teacher realizes she is struggling in math, Judy is sent to a math tutor at the local college and soon is completely into the spirit of college life.

"When Milton Worthy learns his classroom's pet ferret is the evil mastermind behind a dastardly plot for world domination, it's more than just about any kid could handle. But then not every kid is the son of a member of the super-secret, super-awesome Society of Substitutes! Now it's up to Milton and his substitute teacher mom to save Beacher Elementary School before time runs out." -- Page [4] of cover.

When Mrs. Green is out sick, her students worry that their substitute teacher might be a giant monster who will hurl them into outer space.

When their regular teacher is sick, Andy's fourth-grade class gets a substitute teacher, providing lots of opportunities for Andy and his friends to get in trouble.

Sam, Lucy, and Antonio have a new substitute teacher, who happens to be the great-great-grandson of Orson Eerie, the evil scientist whose spirit possesses and infects their elementary school--and the friends are afraid he may be trying to bring Orson back to life.

Mr. Creacher, a multi-tentacled substitute teacher, warns his prankish students not to misbehave, recounting rhyming cautionary tales of the weird, spooky, and unexpected.

When sixth-grade classroom terror Jacob Wonderbar and his friends Sarah and Dexter find a spaceship crashed in the woods near their suburban neighborhood, their discovery leads them to a series of adventures including space travel, substitute teachers, kidnapping, and more.

When Simon's Great Aunt Matilda becomes the substitute teacher for his unruly fifth-grade class, her unique way of looking at things gives the students a new perspective on learning.