In this 1921 image provided by the Library of Congress, smoke billows over Tulsa, Okla., the scene of one of the nation’s most brutal race massacres.

In this 1921 image provided by the Library of Congress, smoke billows over Tulsa, Okla. For decades, when it was discussed at all, the killing of hundreds of people in a prosperous black business district in 1921 was referred to as the Tulsa race riot. Under new standards developed by teachers for approaching the topic, students are encouraged to consider the differences between labeling it a “massacre” instead of a “riot,” as it is still commemorated in state laws. (Alvin C. Krupnick Co./Library of Congress via AP)