A teacher shocked pupils when she showed the class a homemade sex tape featuring herself by mistake.

The unnamed teacher said the accident happened when the video got mixed up in her lesson plan.

The woman quickly admitted the faux pas to officials at Forest Heights Middle School and later in the day called the parents of all the pupils - aged 12-13 - to apologise.

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Many parents are however unhappy with a perceived lack of action that has been taken by the school district authorities in Little Rock, Arkansas since the incident on Wednesday.

Nicholas Tolerson, whose son was in the class, said although he has sympathy for the “apologetic” teacher, he wants accountability.

"She was performing sex acts [in the video]," he told local US news channel KARK-TV. "My concern is with him being in that environment."

"I want something done...My heart goes out to not only my son, but other kids in the classroom."

School officials told the channel that the teacher admitted she showed the inappropriate video in class by mistake and said the incident is under investigation.

The school district said it is determining what disciplinary action should be taken against the teacher, as well as what can to be done to prevent this happening again in the future.