What Katy Did at School is a children's book written by Sarah Chauncey Woolsey under her pen name Susan Coolidge. The Katy book series follow the adventures of a twelve-year-old American girl, Katy Carr, and her family who live in the fictional lakeside Ohio town of Burnet in the 1860s. Katy is a tall untidy tomboy, forever getting into scrapes but wishing to be beautiful and beloved. In this sequel to What Katy Did at School Susan Coolidge describes boarding school life of Katy and her sister Colver. The fictional Carr family was modeled after her own, with Katy Carr inspired by Woolsey herself. The brothers and sisters were modeled on her four younger siblings.