KANNAPOLIS (AP) — Kannapolis City Schools has apologized for an assignment that asked middle school students to compare the value of slaves and white people.

The mother of a student at Kannapolis Middle School posted a picture of the assignment on Facebook, news outlets reported. It was reportedly related to a lesson on the Three-Fifths Compromise. In 1787, the compromise was introduced to classify a slave as three-fifths of a person when apportioning taxes and states’ representation in Congress.

The assignment asked questions such as “How many slaves would be needed to equal at least four white people?”

The principal and superintendent reached out to the parent to apologize, Ellen Boyd of Kannapolis City Schools said. She says the assignment won’t count toward any student’s grade and won’t be given again.

“We have addressed it with the teacher and taken disciplinary action,” Boyd said. She did not say how the teacher was disciplined because it was a “personnel matter.”