A teacher linked to assigning slave-themed math at Beaver Ridge Elementary School has resigned, and parents said they're concerned about how their children are dealing with the assignment and the aftermath.

Gwinnett County School officials announced Wednesday that the teacher quit during a human resources investigation into the origin of the questions, which used references to slave beatings and picking cotton to link lessons about ex-slave and abolitionist Frederick Douglass to math computation. The 20-question assignment was created by one teacher, copied by another and used in four classrooms.

One of the problems: "If Frederick got two beatings per day, how many beatings did he get in one week?"

Sloan Roach, a spokeswoman for Gwinnett Schools, would not identify the teacher, one of four educators in a personnel investigation. But a letter sent to some Beaver Ridge parents Wednesday announced third-grade teacher Luis Rivera had resigned and would be replaced.

"The principal will move forward immediately to fill the vacancy created by this resignation," Roach said in a statement. "As this is a personnel matter, the district will not elaborate further."

Efforts to reach Rivera were unsuccessful.

Beaver Ridge parent Christopher Braxton who complained to the school principal about the third grade math problems on his son's homework said he thinks the resignation should only be the “tip of the iceberg.”

Braxton said that counselors should also be speaking to students impacted by the questions and the fallout. He said his son's class has had a substitute since the investigation began.

"No one knows how the kids have been affected," Braxton said. "No one has sat down to speak with them to see how they are doing with this. My son and a lot of school kids in his class did not want to see their teacher go this way. Some of them are puzzled."

Georgia NAACP president Ed DuBose said he "applauds" the district's investigation of the incident and the resignation, but he thinks that all involved in the incident should be fired, not allowed to quit. He said in addition to counseling for students, parents need reassurance from administrators that this will never happen again.

"This falls short of what we asked for," DuBose said. "We also asked that the superintendent meet with all of the parents and issue an apology. We still maintain that position."

Beaver Ridge, a school of 1,247, has an international student population. Half of the staff is non-white and 88 percent of students are either black or Hispanic.

Roach said she did not know whether the staff had received diversity training. Georgia requires education majors at its colleges to take a class that helps them to understand their cultural experiences and how to relate to the kids they may teach.

Gwinnett County Schools officials said the assignment betrayed such training and did not undergo a review before it was distributed as policy dictates.

Georgia teaching organizations urged the district not to fire the teachers involved in the lessons, but to train them. Tim Callahan, spokesman for the Professional Association of Georgia Educators, called this a " teachable moment" for students and adults.

Education experts say the best way to win back parents after an incident like this is to be honest about the mistake.

“The teachers themselves need to apologize and directly acknowledge that a mistake was made and then start trying to rebuild confidence,” said Desha L. Williams, a math professor at Kennesaw State University.