Oh boy, is class a loaded issue in A Little Princess or what? Sara's class in society is in flux throughout the book—and when it changes, it's quite interesting to see how other characters react to her. Some, like Lavinia and Miss Minchin, treat her completely differently when she is rich and has standing in society vs. when she is poor and "nameless." Others, like Ermengarde and Lottie, couldn't care less. They see Sara as a human being no matter what her class is and they want to be her friend. Any guesses as to which group is the more reasonable and compassionate?
The more narrow-minded characters in the book, like Lavinia, only judge people by their social station, and therefore they never grow as people.
Sara doesn't limit her friends to members of her own class—she befriends both Becky and the Lascar next door. This offers her more opportunities for relationships than other people have.