About two dozen girls and boys file into the classroom and sit cross-legged on the floor facing a small whiteboard, attention focused on their teacher as the day's lesson begins.
The teacher holds up a Kalashnikov rifle and calls on a boy named Daud.
"Why do we use this?"
"To defend the faith," the young student responds.
"Whose heads will we hit with this?"
"Infidels."
A similar exchange follows on the topics of grenades and handguns. Later, the children take turns learning to shoot. The subject of the lesson? Struggle, or armed jihad, on behalf of the Islamic State group, also known as ISIS or ISIL.
The disturbing scene was captured by a journalist with PBS' Frontline, who for the first time went inside the ISIS-controlled territory in Afghanistan to better understand the violent terror network.
While ISIS' expansion in Iraq and Syria has made international headlines, Frontline found the group is gaining ground in Afghanistan. In addition to marrying local women and collecting taxes, ISIS is running schools to educate children as young as 3 years old in its controlled territories there.
Reporter Najibullah Quraishi put his own life on the line to better understand how the group that has claimed responsibility for bloodshed around the world, including the attacks in Paris and the downing of a Russian passenger plane, exerts its power and trains its members.
"They are completely different than the Taliban," Quraishi says in the piece. "They are not after one country or one place or one district. Their aim is to have their group, to have their network all over the world."
Getting the story took eight months and incredible personal risk for the married father, who has covered intense and dangerous subjects, such as the war in Afghanistan, the Taliban, and the local child slavery practice known as bacha bazi. Quraishi, who lives in London, was not immediately available for an interview with Refinery29. But he told Poynter's Al Tompkins that despite the threat, he felt a need to better understand what he called "the most dangerous people I have ever seen.”
He told Poynter that watching the children learning jihad was "shocking" and "the most horrible moment I felt ever in my journalism life.”
"I cannot see any bright future for Afghanistan," he said.
The full segment, ISIS in Afghanistan, aired on PBS on Tuesday. It is available on the Frontline YouTube page here.