One of the most interesting things I have learned recently, acting as both student and teacher of history, is that we are taught substantially different kinds of history as we get older. A good example of this is the contrast between the moral simplicity of the Civil War as it is taught to high schoolers, and the relative moral complexity of the Civil War as college students discover it; even more interesting, I think, is that this tends to be true, no matter what part of the country you are from.
By this, I mean that whether you learn about it as a "War of Northern Aggression" or a conflict between the immoral slaveholding Confederacy and the righteous abolitionist Union, you will ultimately find that neither conception follows from the historical data. Ultimately, the centrality of the battle for state sovereignty, along with the near-universal racism of most northerners, will force students of the war to recognize the moral subtleties and primacy of practical concerns and/or political expediency. Such nuances seem (at least to me) to be withheld from younger students learning about the war.
Unfortunately, not all students have the opportunity to take the kind of advanced history courses that reveal the moral and political ambiguities of the war. The Civil War is merely one example of a period/event that we learn to see in black and white, and it is a good one because 150+ years have failed to sufficiently corrode the time-honored convictions (held by North and South alike) that undermined Reconstruction and rewrote fact into a fanciful romantic reunion that sealed up the tortured seeds of the war to rot beneath our feet, so that we are only reminded of them occasionally, when the scent of putrefaction slithers up into the rarefied air of our liberal modern world.
We can only unmask the fictions of history (as it has been told to us) through probing and conscientious investigation of the historical record, and this kind of study requires not only intellectual curiosity, but also a flexible mind, capable of integrating even the most unexpected or unwelcome information into an ever-changing narrative of a past that can never even aspire to reflect "reality."