This kind of conversation belongs in a social studies class and should be moderated by an unbiased individual for the student's benefit.
But as I'm sure that we have all read 'of mice and men' I think the teacher is trying to parallel how the workers were treated in the story with how they are actually being treated now. The article was probably just some information to show how the workers are being treated nowadays.
Also note that of mice and men is centered around two migrant workers looking for the american dream. Illegal immigrants are in a way, on this same mission.
Funny that I think about it, Lenny breaks the law, and his friend George kills him for it. Makes you think if you are relating it to illegal immigration, illegal immigrants are breaking the law, and as lenny was unable to get the goal he always wanted because he did something wrong, illegal immigrants breaking the law will also never be able to achieve the american dream.