This movie is based on a true story. It is about students under forced integration living in desperate circumstances in a time and place of poverty and gang violence. Racism strongly divides the students and education is the least of their concerns. Teachers have given up on them and strive mainly to warehouse them.
A naive optimistic teacher finds ways to inspire the students and give them hope along with genuine opportunity for education through journaling and reading that they relate to, and building classroom community. She gives her whole life to the class at the expense of her marriage and two part time jobs to support her supply needs for her day job.
Union teachers are given a bad rap here as anti-reform and out of touch - not an accurate depiction as a generalization.
There is a strong anti-racism message. The movie has a good overall message but is a bit sappy and yes, I do think unrealistic in terms of mass application.