Final answer:
Margaret Sanger worked as a nurse at the Henry Street Settlement in New York, a part of the settlement house movement that provided key services and healthcare for working-class women.
Step-by-step explanation:
Margaret Sanger was a nurse from New York who dedicated her life to advocating for the legalization of contraceptives and was the founder of Planned Parenthood. Sanger worked in the settlement house movement, which was instrumental in providing services for the working class, especially working-class women who needed support and education on various topics, including healthcare. She worked as a nurse in the Henry Street Settlement, founded by Lillian Wald in New York. This movement offered services such as child daycare, evening classes, libraries, gym facilities, and free health care, which were crucial for the empowerment and well-being of women at the time.