There are very few conservative teachers who teach the Lost Cause version of the civil war. There are some debates within the historical community so it isn't really fully settled though. Many in the North were talking about the federal government trampling state's rights and they weren't talking about slavery so it isn't quite as simple as you make it out to be.

I assume you are talking about slavery when it comes to your last point? If that is the case there are no conservative teachers denying slavery happening in the US including the fact that some of the founding fathers had slaves.