Regarding the role of religion in the conflict they should learn the words to both Dixie and the Battle Hymn of the Republic then compare them.
This is a really opportunity to establish in everyone’s mind that the Republican Party was anti-slavery and that Abe Lincoln was a Republican. You would be shocked at how many people do not know that.
They should teach it accurately. The anti-slave faction was the Republicans. The pro-slave faction -- whether it be northern copperheads or southern successionists -- were Democrats.
Yes, secession was done over slavery. However, the Union fought to end secession, to preserve the Union, NOT to end slavery.
If Lincoln had stayed his hand though, I think something would of worked out in ten or twenty years at most, which would brought a re-union, AND ended slavery in the South WITHOUT over 1/2 Million dead...