A top student in her secondary school, Curie could not attend the men-only University of Warsaw. She instead continued her education in Warsaw's "floating university," a set of underground, informal classes held in secret. Both Curie and her sister Bronya dreamed of going abroad to earn an official degree, but they lacked the financial resources to pay for more schooling. Undeterred, Curie worked out a deal with her sister. She would work to support Bronya while she was in school and Bronya would return the favor after she completed her studies.