I've recently come to believe that a very important course missing from the high school curriculum is the history of science. The course as it's taught is primarily about learning facts (laws, how to draw atoms, and so forth) and solving problems; both very important. But the emphasis is almost exclusively on what we know and not how we know it.
When you take a step back and look at a history class, it's really is the history of humanity learning to get along (through the nicer bits of diplomacy and the uglier bits called wars.) The moral of twentieth century history is that we have almost but not completely got that figured out. Major powers don't go to war and haven't for decades.
Similarly, the history of science is the history of humanity learning what it should take to change our minds. In an excerpt from a longer interview at Skeptic Magazine, Lawrence Krauss explains why most people don't understand how scientific knowledge advances.
On a recent episode of Quirks and Quarks on CBC I was introduced to the term pessimistic meta-induction hypothesis. Science has told us that much of what we thought was true ten years ago is now false. So ten years from now most of what we now think of as true will be false. So any fact we disagree with now can safely be ignored since it will eventually be discovered to be wrong anyway.
You'd be surprised how many people believe that.