Hmm, you know what? I got the history of science from the time I was a wee lass, and particularly in all my biology classes from middle school on, and I don't think just teaching the history of science is enough. The most common reaction (this was mine as well) is "Why are we learning this stuff if we know it's not true any more?"

So I honestly don't imagine teaching it earlier would change anything.

Teaching it differently, however... Which is why I think your class is a good idea, as the living process of research and the changing understanding of concepts in science is really fun. I *got* it once I started working in a research lab at the age of 19. But not before then.