A Fine, Fine School by Sharon Creech (2013)
A Fine, Fine School is a delight for kids, with its colorful illustrations and gentle comeuppance for a well-meaning principal who learns that learning outside of school can be just as important as being in school. Tillie goes to a fine, fine school where kids learn about dinosaurs, build pyramids, and paint portraits. When her principal decides to call all the students and teachers together for an announcement, no one could have predicted he would say that there will be school on Saturdays! Soon everyone goes to school on Sundays, holidays, and even the summer. He loves school so much that he forgets to give anyone time off!