How did Antonia change after her fathers death?

Jim notices that Antonia has become a very hard worker. When Ántonia returns from plowing the fields, Jim is amazed at what a strong, young girl of fifteen she has become. She is proud of how much work she can do and says she doesn't want to go to school because she is happy to be working with Ambrosch like a man. Jim worries that Ántonia is becoming boastful like her mother, but then he notices that she is secretly crying. As he helps her with some chores, she makes him promise to tell her the things he learns in school and not to forget her father, who also went to school.