The truth is not taught today. The victors earned the right to re-write history.
Truth: The Civil War was not about slavery...in the beginning. In the beginning it was about diametrically opposed economic objectives. The North was a budding manufacturing economy and the South was an Agronomy economy. The North could not export its goods to Europe because they were more expensive and Europe's goods were less expensive when imported here so the North found it hard to compete in a free economy. The South on the other hand had cheap labor in the form of slaves and had favorable balance of trade with Europe in cotton.
The North implemented import tarrifs on European goods to prop up the North's manufacturing economy (to make European goods artificially more expensive) England retaliated by placing import tarrifs on Cotton from the South.
What transpired from there was all window dressing. When the North could not get general populous support for the war, they pivoted to the subject of slavery to win support for the war.
Also truth. It was the democrats who opposed ending slavery and it was the republicans who wanted to end slavery.
Weird how the truth gets twisted.....