I have problem Marx being taught as Marx. I know backwards and forwards, far better even the self-professed Marxists. In fact, few Marxists have ever even read Marx; if they had, they wouldn't be Marxists. The schools don't teach Marx as Marx, though; they teach Marxism by another name, usually "patriotism."
If you want to innoculate your kids against Marxism, you make them read Marx, and then discuss it with them....why Marx demonizes the middle class, and avoids even mentioning the aristocracy; why Marx creates the strawman of "Capitalism," and avoids any real discussion of free markets.
If you want your kids to understand trade and national wealth, you have them read Smith's 'Wealth of Nations', and discuss the merits of mercantilism and the role of "free trade" in the pillaging of national wealth.
If you want your kids to understand why America allied itself with Communist Russia in WW2, and provoked Japan into conflict, instead of letting Japan and Germany crush the international Communist threat, and dealing with a the fallout, you might them to read Skousen and Sutton, and to understand that the FDR administration propped up the fledgling USSR, while it was simultaneously confiscating gold from Americans, right down to their wedding bands.
If you want your kids to understand Hitler's fixation on "The Jews," you will probably want them to read 'Mein Kampf', and to discuss with them why Hitler blamed them for international communism and the erosion of nationalism, and whether a man who allied himself with racially diverse nations was truly the blindly hateful xenophobe he's made out to be.