A teacher has quit after admitting he watched porn during a physics lesson with 13 and 14-year-olds, even though he said it was “unintentional.”

Excruciating footage showed Razif Nurgaliev, 62, smirking at X-rated scenes on his screen, “seemingly unaware” they were also appearing on the classroom monitor. The students, left stunned, watched as the veteran teacher “gawped at the pornography” after setting work for the class in Tashkinovo village, near Neftekamsk, Russia.

He had “forgotten his laptop was connected to the electronic blackboard,” reports said. One pupil secretly filmed the incident from behind his physics textbook.

At first, a school source tried to shift the blame, claiming the teenagers played a prank on him. But Nurgaliev admitted to officials, “I clicked on something, and some website opened.”

He insisted he was only trying to access an online journal and had “not intended to watch the explicit material.” Despite nearly 40 years at the school, he resigned following the incident.