Ada Twist is a very curious girl who shows perseverance by asking questions and performing experiments to find things out and understand the world.

Retired scientist Miss Tracy comes to Ella Mentry School to teach about the planets and the solar system and casts A.J. as Uranus in the school play.

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.

After Rosie Revere's Uncle Ned gets carried away wearing his famous helium pants, Ada and her friends must find a way to get him down before he floats too far away.

In her first week in fourth grade (exiled to a new school because of redistricting) Curious decides that she wants to be a scientist, and her first task is to sharpen her powers of observation by observing her large family, three older sisters and three younger brothers--and try and become effectively invisible in her new class.

Eerie Elementary is planning a big Halloween-type celebration for Eerie Day, including hosting a "haunted house" at the school itself; but the spirit of the evil scientist Orson Eerie sees this as the chance to finally triumph over the intrepid hall moniters, Sam, Lucy, and Antonio--and it is up to them to prevent a catastrophe and perhaps even defeat Orson and banish him from the school forever.

Dr. Morley is about to embark on a quest to the northernmost tip of the world, in search of a creature that everyone talks about but nobody has ever seen: the giant Arctic jellyfish. After years of research and hard work, she gathers a highly trained crew and a ship full of special equipment and sets sail for the vast icy reaches of the Arctic. Will she find what she is searching for? Or will it find her?