If the newest student at Lower Merion High School was nervous, standing before several hundred of his peers, it didn't show.

Mahmoud Hallak, 16, certainly knew his material.

He'd lived his subject.

The slight teen with a pile of thick, dark hair waited impassively as the auditorium filled one day last week, his tie loosened, white oxford shirt untucked over crisp jeans and covering a thin, dark scar at the waist.

Susan Naples, who teaches U.S. history at the Main Line school, warned the audience before Hallak started. "His presentation has some harsh realities and photographs," she said.

Hallak's topic was the violence in Syria. He's from Aleppo, where in May 2011, his father, a physician who ran the country's only eating-disorders clinic, was murdered.

Twice I've written columns about Hallak's uncle, Hazem Hallak, a medical researcher who lives in Merion Park and who is trying to call attention to the killing in Syria. Hazem Hallak and his family are sponsoring his nephew, who arrived here two months ago after fleeing with his mother and two sisters to Turkey.

The auditorium hushed as Hallak began. He showed a map, convinced that most of his new friends don't have a clue that Syria is not in Africa. A quick history of the Assad family's rise to power set up his account of the unrest that began in March 2011, when schoolboys in a remote town, Dara'a, sprayed walls with graffiti that criticized the regime.

The boys, ages 10 to 15, were arrested, beaten, and tortured. When their fathers met with Atef Najib, a cousin of the president, to demand their release, they were told to forget the children, make new ones.

Hallak put a quotation from Najib up on the screen: "If you can't make your own children, send us your wives, and we'll make them for you."

That, Hallak told his classmates, was the worst thing you could have said to the men. "Kill them, but don't say such things."

The protests spread to the cities and to Aleppo, the financial capital, he said. When he got to his father's disappearance, he became clinical, procedural, as though the events had happened to someone else.

Protesters were hurt in a rally in the countryside. Sakher Hallak, 43, tended to some of the wounded. "His conscience told him to do that," his son said.

While the doctor was driving home from the office soon afterward, someone grabbed him. Members of the Mukhabarat, the state intelligence agency, visited his wife a few days later and said Sakher Hallak was fine, and would be home shortly. His body was found dumped along a roadside.

"He was tortured, actually," is all his son said of this.

Mahmoud Hallak showed more pictures: a father wailing over his dead son; a man providing cover with an automatic weapon so he could run across the street; a leveled hospital.

He told how he took to Skype under an assumed name to communicate with others who opposed the regime, how during a rally, army troops appeared out of nowhere and started shooting, how as he was running he felt a pain in his right side - fragments, he thinks, from a grenade. A friend helped bandage his bleeding waist.

For nearly 50 minutes, his voice was the only sound in the room. Then, cheering. A dozen students surrounded him, pumping his hand. A girl he didn't know hugged him. For the first time, he smiled.

Because his school had burned down, Hallak had no transcripts, so placing him at Lower Merion was tricky, says his counselor, Marsha Rosen. After testing, he joined the 11th grade, not 12th, which would have been his year back home.

His math and science were strong. Even his command of English earned him a spot in honors. He's told his counselor he hopes to stay in this country to go to college, although that would mean leaving behind his mother and sisters, who, unlike him, didn't have a U.S visa in their passports before the conflict.

His cousins - Dania, 16, and Alden, 14 - are making sure he gets a proper introduction to this country. He's met Santa at the Comcast Center, tried his first candy cane - "Very tasty," he pronounced. "Minty sweet." He now owns a hoodie.

Hallak said he was surprised to see how much Americans work and study. "It's not like the movies, where kids are always going to parties," he said.

He's reading The Great Gatsby in English, learning about World War I, and wrestling with trigonometry and physics. His plan is to study medicine, like his father.

"That," he said, "was his dream."

Contact Daniel Rubin at 215-854-5917, drubin@phillynews.com, or follow on Twitter @danielrubin or Facebook at http://ph.ly/DanRubin