Who is Sarah ("Sadie") Delany from Having Our Say: The Delany Sisters' First 100 Years and what is their importance?

Sadie was Henry and Nanny's second child. She was born in Virginia, was known as a Mama's girl, and was the first of the Delany children to attend college. Sarah became a teacher, working in the New York public school system throughout her teaching career. She is described as popular and well loved among her students and co-workers. Sadie never married.