Carl Marx is alive and well.
Unfortunately the only place he can still survive in the world is in the halls of American universities. We've been conned into accepting a lie that all ideas and systems of belief and cultures are equally valid and deserving of respect. Some are not. Some ideas fail miserably, and cause the death of millions almost every time they are tried. Some cultures are brutal murderous and backward, and should not be respected or accepted. But we in our misguided, open-minded, and free society allowed marxism to fester in our schools, and now it threatens to destroy us. It should be stamped out, like the disease it is.
You do not teach children that slavery is ok. It's not acceptable. Neither is marxism or communism. Those ideas have no place in education, other than as a history of oppression and mass murder.