Pupils were left gobsmacked when they were shown a homemade sex tape featuring their teacher!
The unnamed teacher said the accident happened when the video got mixed up in her lesson plan.
The woman quickly admitted the mistake to officials at Forest Heights Middle School then called the parents of all the pupils - aged 12 and13 - to apologise.
But parents weren't happy with the apology and complained to school district authorities in Little Rock, Arkansas.
Nicholas Tolerson, whose son was in the class, told local TV news: "She was performing sex acts (in the video). 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 said the teacher admitted she showed the inappropriate video in class by mistake and said the incident is under investigation.
The school district said it was deciding what disciplinary action should be taken against the teacher, as well as what can to be done to prevent a similar incident happening again in the future.