If schools don't do a better job teaching about slavery, students won't be able to understand the country's past or its present, according to the Southern Poverty Law Center.

On Thursday the SPLC's Teaching Tolerance Project released a report titled "Teaching Hard History: American Slavery." The report finds specific fault with Alabama curriculum; Maureen Costello, a former history teacher who is director of Teaching Tolerance, said a yearlong survey leads her to think inadequate teaching of slavery is a pervasive national issue.

"If we are to move past our racial differences, schools must do a better job of teaching American slavery and all the ways it continues to impact American society, including poverty rates, mass incarceration and education," Costello said in a statement announcing the release of the report. "This report places an urgent call on educators, curriculum writers and policy makers to confront the harsh realities of slavery and racial injustice. Learning about slavery is essential for us to bridge the racial differences that continue to divide our nation."

The SPLC statement says that "Only 8 percent of high school seniors surveyed could identify slavery as the central cause of the Civil War. Most didn't know an amendment to the U.S. Constitution formally ended slavery. Fewer than half (44 percent) correctly answered that slavery was legal in all colonies during the American Revolution."

As of Thursday, the report is available for download. The SPLC also is offering a selection of resources for teachers.

The report's specific look at Alabama's curriculum alleges that it entirely fails to cover a range of key concepts:

The 2010 Alabama Course of Study for Social Studies (revised in 2013) introduces the Civil War in first grade and the Emancipation Proclamation in second grade, but delays the first mention of slavery until third and fourth grade, when it is included in a list of causes of the Civil War. Harriet Tubman is on a second-grade list of exemplary Americans, but there is no mention of the institution she struggled against. This is history without context. It misses an opportunity to give students a full picture of what made figures like Tubman so remarkable, while sanitizing the past. In third and fourth grade, the causes of the Civil War are listed as "sectionalism, slavery, states' rights and economic disagreements," a disingenuous representation that obscures slavery's central role in causing the Civil War, insofar as slavery was the underlying cause of factors like sectionalism, states' rights and economic disagreements. In fifth and sixth grade, students are asked to "[d]escribe colonial economic life and labor systems in the Americas," including "[r]ecognizing centers of slave trade in the Western Hemisphere and the establishment of the Triangular Trade Route." Later, the standards cover the Missouri Compromise and Nat Turner's insurrection, but not the conditions that caused these events. In high school, abolitionism receives some coverage, but the institution it protested receives only a passing mention in the context of the Triangular Trade. In short, Alabama's Course of Study fails in its responsibility to set meaningful expectations for learning about the history of American slavery--a history that is essential to understand key events in Alabama's own history and relevant for a substantial number of Alabama's students whose lives even today are shaped by this past.

A request for comment from the Alabama State Department of Education was pending as this story was published. The state currently uses a Social Studies Course of Study approved in 2010. It'll begin a review in 2020, leading to new standards going into effect in 2022.

The report's final recommendations include a call to improve teaching about slavery and fully integrate it into U.S. History and for states and local districts to improve textbooks and curriculum.

Despite the finding that "teachers are serious about teaching slavery" despite the challenges that come with the subject, the report maintains that individual efforts aren't enough: "This nation needs an intervention in the ways that we teach and learn about slavery," it says.