Among 12th-graders, only 8 percent could identify slavery as the cause of the Civil War. Fewer than one-third (32 percent) correctly named the 13th Amendment as the formal end of U.S. slavery, with a slightly higher share (35 percent) choosing the Emancipation Proclamation. And fewer than half (46 percent) identified the “Middle Passage” as the transport of enslaved Africans across the Atlantic Ocean to North America.

Maureen Costello, the director of Teaching Tolerance, said the research, conducted in 2017, revealed the urgent need for schools to do a better job of teaching slavery. “Students are being deprived of the truth about our history [and] the materials that teachers have are not particularly good,” she said. “I would hope that students would look at this and realize that they deserve to know better … and teachers need to know there are better ways to teach this [topic].”

The student results, which the report labels “dismal,” extend beyond factual errors to a failure to grasp key concepts underpinning the nature and legacy of slavery. Fewer than one-quarter (22 percent) of participating high-school seniors knew that “protections for slavery were embedded in [America’s] founding documents”—that rather than a “peculiar institution” of the South, slavery was a Constitutionally enshrined right. And fewer than four in 10 students surveyed (39 percent) understood how slavery “shaped the fundamental beliefs of Americans about race and whiteness.”

Examining the teachers’ survey results might help explain why students struggled to answer questions on American enslavement: Educators are struggling themselves. While teachers overwhelmingly (92 percent) claim they are “comfortable discussing slavery” in their classroom, their teaching practices reveal profound lapses. Only slightly more than half (52 percent) teach their students about slavery’s legal roots in the nation’s founding documents, while just 53 percent emphasize the extent of slavery outside of the antebellum South. And 54 percent teach the continuing legacy of slavery in today’s society.

Additionally, dozens of teachers rely on “simulations”—role-playing and games—to teach slavery, a method that Teaching Tolerance has warned against on the grounds that it can lead to stereotypes and oversimplification. Meanwhile, a large majority—73 percent—use “slaves” when talking about slavery in the classroom instead of “enslaved persons” (49 percent), the latter term of which has gained favor for emphasizing the humanity of those forced into bondage.

The overwhelming majority of teachers who participated in the survey (90 percent) are somehow affiliated with Teaching Tolerance and its learning materials. Costello said this indicates the problems revealed in the survey results could be much more pervasive than the findings suggest. “If anything, I think [this collection of survey respondents] is a group that’s more sensitive to issues of race, more likely to confront them in classrooms” compared to the broader teacher workforce, she explained, adding that the findings are “a silhouette of the problem.” Similarly, many of those surveyed were elementary-school teachers, which Costello said was noteworthy considering the ability of slavery education in the early grades to form the narrative—the “fake history”—that students carry through high school.