I think we should leave the issue of slavery out of it entirely to avoid conflict.
It was one of the major issues that the South felt like its rights were being trampled on, but it was no the only one.
The war was over state's rights and how power should be divided up, it had been a longstanding issue ever since the Articles of the Confederation were nulled in favor of the US Constitution. (The Bills of Rights were the first amendments to it and it was penned to appease the Anti-Federalists which were forebearers to the Confederates)
In short, the war was about States Rights, and Preserving the Union.
Slavery was just one of the issues that moved things into motion, but since its such a sensitive subject we should just not mention it.