Slavery should not be taught. It is not a subject. An accurate teaching of History is what should be taught. Causes, effects, impacts of historical events are key to an education in History which augments understanding historical event dates, locations, etc. Example, to teach pre-Civil War history includes learning about the great awakening, regional issues like economics, political trends and a key issue in all of those was how and why slavery was involved.
Africans believed that humans could be property but land could not be property.