A teacher in the US state of Georgia has been suspended after allowing students to dress in mock Ku Klux Klan robes for a project.
The teacher had asked four students, none of whom were black, to re-enact scenes from history for a class film.
Officials said the teacher had used poor judgement. Georgia has a history of violent racial tension and students and parents were upset by the incident.
The teacher, who is white, acknowledged it was a mistake to film the scene.
"It was poor judgement on my part," Catherine Ariemma told the Associated Press news agency.
The class at Lumpkin County High School near Atlanta included no black children, and the school system is roughly 90% white.
The Ku Klux Klan is one of the oldest and most infamous hate groups in the US and was known for the white robes and cone-shaped hoods members wore at rallies.
Founded as a vigilante group amid the turmoil after the US civil war, the Klan violently opposed civil rights for African Americans, although the group also turned its ire toward Jews, Catholics and immigrants, according to the Southern Poverty Law Center, which tracks hate groups.
Its membership and influence have waned in recent decades.
Ms Ariemma told US media she had asked the students to film scenes from American history for a course combining US history with film study. For the scene in question, the students were exploring American racism.
"This is a film about racism and we have to discuss racism in our society," she said.
"You can't discuss racism and not include the Klan."
Ms Ariemma, a teacher for nearly six years, said the students had brought in bed sheets and cone-shaped party hats to make their costumes.
Other students observed four of their robed classmates walking through the cafeteria to another location in the school where another student filmed the scene.
Some African-American students and parents complained to school administrators and Ms Ariemma was suspended. She could face further disciplinary measures.
"We determined, obviously, that she used extremely poor judgment," school system superintendent Dewey Moye told the Atlanta Journal-Constitution newspaper.