In the movie Spanglish, Flor, the then housekeeper of Claskys' home was quite infuriated with Deborah's decision to enroll Christina in the private school Bernice, her daughter, was attending then.
A quick look in the Wikipedia's plot summary of the movie brings one's notice to this particular line:
She enrolls Cristina into a private school with Bernice, upsetting Flor, who wants Cristina to keep in touch with her Mexican roots and working-class values.
This pretty much answers the why query.
But, the question mark for me still remains: how does by attending a private school, one loses her ethnic roots and working-class values?
At the end of the movie, Flor asked her 'the most important question of her life, at a very young age'
"Is what you want for yourself to become someone very different than me?"
I'm not getting how by living with Claskys' and attending the private school, she would be different from her mother.
I'm just not somewhat getting the objection and the point of view of Flor.