What happened between Esperanza and the nun from her school?

Esperanza wants to eat in the school lunch room, the canteen, because she is under the impression that "the special kids" eat there. To her, not returning home for lunch seems to be an exciting prospect. After finally convincing her mother to let her take her rice sandwich to the canteen, Esperanza's illusions are shattered when a nun makes her point to her house from the window and tells her she lives too close and cannot eat there again.