Although you wrote that "tongue in cheek", you are close to the truth. I really don't know how they will teach it but maybe a "coalition of racists" attempted to secede from the Union or some such tripe. Scary as hell.
The Articles of Confederation referred to here were the precedent to the current US Constitution prescribing the cooperation of the states in existence at that time.
Other than slavery was legal, just as it was for a long time under the Constitution, there really is no relationship to the states which seceded from the union.