The question then prompts students to set a price for a slave, noting, “These could be worth a lot.”
A photograph of the question was posted Sunday on Facebook.
Other questions in the assignment focus on trading commodities like fish, grains, lumber and turpentine, KTVI reported.
John Bowman, president of the St. Louis County Chapter of the NAACP, said the assignment was “sad and unacceptable.”
"The position of the NAACP is we need a public apology," Bowman told KTVI. "There also needs to be some serious and immediate implicit bias, cultural bias, cultural difference training."
In his letter to parents, Booker said he met with the teacher, who "expressed significant remorse," the Post-Dispatch reported.
The incident is under investigation, and Booker told the newspaper he plans to institute cultural bias training for his teachers and staff members.
“We are working together to ensure all students and families feel valued and respected at Blades Elementary,” Booker wrote.