Sometimes people use the term, "Middle class," whose economical income is middle in the society. I, however, think it is wrong expression. Because, the distinguishing should base on the difference of their behavior, as if in the middle age the behavior of slaves are totally different from that of nobles.
Now regular schools teach this society has no class; at least it is true in South Korea. But we can clearly see there is Class based on behavior. Although the system always try to hide the truth, it always fail, because in real world people behave differently, and it cause conflict and fighting. There could not be peace between them. The people who has power try to change law to make their benefit better. On the other hand the people who don't have power to protect themselves use physical violence or 'illegal acts.'; their behavior has become illegal by the people who has power.
Here is the point. Who tells us there is class in this society? I don't find anybody except Marx.
Then, why does the system try to hide the truth? Why does the system waste time and resources in school to hide it? I think it is because the capitalism society has justified its appearing, criticizing the problem of slavery. So if the system accept the fact that the capitalism is just different version of 'wage slavery', it loses the way to justify.