Nancy, who likes to use fancy words, cannot think of a fancy enough project to commemorate the 100th day of school.

"In their fourth adventure, classroom mice Fergus and Zeke--after a few false starts--jump into a creative project to help the kids mark the one hundredth day of school. 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...

Harry Bergen-Murphy does not feel ready when he starts first grade, but by day 100 he has become an expert on several important things, including being a first-grader.