A Missouri elementary school teacher has been placed on administrative leave for giving students an assignment that asked them to "set your price for a slave."

The in-class work was given to a 5th grade Social Studies class last week at Blades Elementary School in St. Louis. School administrators became aware of it over the weekend after a photo of the assignment was posted on social media.

"It is so wrong on so many levels," Lee Hart wrote on Facebook. Hart said her friend's child attends the school and was given the assignment.

"This was supposedly a westward expansion lesson," Hart posted. "Some were given food, wood, water, and slaves!!!!!"

The assignment, a copy of which was provided to NBC News by the Mehlville School District, instructs students to set a price for a number of items such as grain, fruit, fish, a container of oil and a cow. The last question asks the children to pick a price for a slave.

"You own a plantation or farm and therefore need more workers," the lesson states. "You begin to get involved in the slave trade industry and have slaves work on your farm. Your product to trade is slaves."

Blades Elementary School principal Jeremy Booker said the educator, who has not been identified, was attempting to teach students about "market practices" and the class was "learning about having goods, needing goods and obtaining goods and how that influenced early settlement in America."

"Some students who participated in this assignment were prompted to consider how plantation owners traded for goods and slaves," he said in a letter to the school community.

"The assignment was culturally insensitive," he said, adding that the teacher "has expressed significant remorse."

Chris Gaines, Superintendent for Mehlville School District, said that asking students to participate in an activity where they have to put a price tag on another person is unacceptable.

"Racism of any kind, even inadvertently stemming from cultural bias, is wrong and is not who we aspire to be as a school district," he said in a letter addressed to the staff and district family members. "I am sorry and disappointed that this happened in our school."

A spokesman for the district told NBC News that the teacher has been placed on administrative leave.

Booker said all teachers and staff will be provided "professional development on cultural bias."