“We understand the seriousness of this matter, particularly in light of the events taking place in our country at this time,” the district’s statement said. “We want to ensure that our students, parents, staff and community know that we are giving this matter our full attention.”

The offensive assignment in South Carolina is at least the third this year that has resulted in accusations of racial insensitivity.

In February, second graders at Windsor Hills Elementary School in Los Angeles were asked to solve a word problem: “The master needed 192 slaves to work on plantation in the cotton fields. The fields could fill 75 bags of cotton. Only 96 slaves were able to pick cotton for that day. The missus needed them in the Big House to prepare for the Annual Picnic. How many more slaves are needed in the cotton fields?” (A similar assignment was given to third graders in Gwinnett County, Ga., in 2012: “If Frederick got two beatings per day,” it asked, “how many beatings did he get in one week?”)

And in April, a teacher at Fox Chapel Middle School in Spring Hill, Fla., was fired after assigning a work sheet that asked students how comfortable they would be in a variety of circumstances: “a group of black men are walking towards you on the street,” for example, or “the young man sitting next to you on the plane is Arab.”

Mr. Cooper emphasized this context in an interview on Tuesday.

“I think it’s very important that the larger issue does not go away,” he said. “I think the conversation needs to continue. The conversation should be elevated but yet go deeper. I think the larger issue of class assignments and curriculums for African-American children that are more culturally sensitive and less offensive is where the conversation should go.

“I think that’s the larger issue, and that’s what we as a family do not want to get lost in this situation.”

And what about his nephew, who was crying on Thursday?

“Today he is in great spirits,” Mr. Cooper said. “He’s so proud of himself today, because he spoke up for himself.”