Fergus and Zeke love being the class pets in Miss Maxwell's classroom, and they do everything the students do. But when the kids start collecting items and doing gym challenges and making projects to celebrate the one hundredth day of school, the mice can't seem to find a way to join in. One hundred miles is a very long distance when you're running on your spinny wheel. One hundred seconds is a very short time when you're trying to take a nap. Stacking one hundred wood chips makes a tower that tips and falls before you're even halfway done. And writing a story with exactly one hundred words means abandoning your characters in the middle of the action! Will these two classroom mice ever come up with the perfect project to celebrate the one hundredth day?