In a very disturbing case of alleged racism, a white middle school teacher from The Bronx borough in New York has come under fire for using black students in her class to demonstrate a lesson on US slavery.

Patricia Cummings allegedly forced three black students to lie on the floor and then stepped on their backs to discuss slavery lessons. "You see how it was to be a slave? How does it feel?" Cummings reportedly said following the cruel demonstration.

Although it was not clear when the incident took place, she now faces allegations of going too far in teaching her students how blacks were forced into the slavery system by white people because of their skin colour. She was discussing the infamous Middle Passage in the class when the incident happened, New York Daily News reported.

The Middle Passage refers to the time when Africans, heavily packed onto ships, were transported across the Atlantic to America as part of the global slave trade. The journey used to take three to four months, during which many died of hunger and torture. The enslaved men used to be chained in rows during transportation.

Several students testified against the teacher's act. One of her students, who did not want to be identified, said that it "was a lesson about slavery and the Triangle Trade. She picked three of the black kids" and asked them to get on the floor in front of the whole class. The boy added that when one girl from three of black students jokingly said that she felt fine after lying on the floor, Cummings "put her foot on her back and said 'How does it feel?'"

The social studies teacher was removed after the incident came to notice but, returned to school on Thursday (1 February) morning. She was reassigned away from the students later in the day after the New York Daily News registered a complaint with the city education department.

An investigation has been launched into Cummings' conduct, who has been teaching at the middle school since September 2016.

Education Department spokeswoman Toya Holness said, "While the investigation has not been completed, these are deeply disturbing allegations, and the alleged behaviour has no place in our schools or in society."

The school's principal, Principal Giulia Cox, reportedly declined to comment on the case when New York Daily News contacted.