Sorensen confides he's never heard of IM or Facebook, and as he shuffled to the podium on a student's arm, it seemed unlikely he would connect with the teenagers, whose parents were being born as Kennedy arrived at the White House.
But that impression soon dissipated.
"I don't see much, but I have more vision than the president of the United States," Sorensen joked to loud applause.
He had plenty more to say about President Bush, including his "lack of judgment" and diplomacy in handling the threats after 9/11.
Speech writers wield untold power among voters, and Sorensen is considered one of the modern day best.
George Washington got help from Thomas Jefferson, James Madison, and Alexander Hamilton. Franklin Roosevelt often turned to playwright Robert Sherwood, and Dwight Eisenhower used journalist Emmet Hughes.
But Sorensen was more than a speechwriter, and his closeness and access to Kennedy was "unique" in U.S. history, say presidential scholars.
Graduating first in his class at University of Nebraska Law School, Sorensen -- at the advice of his college adviser -- took one year off his age to get a job as a legal aide in Kennedy's Senate office.
"The rest is history," he said.
He helped Kennedy draft the Pulitzer-Prize winning "Profiles in Courage," though he consistently denied charges that he had been its author.
After Kennedy's assassination, he wrote Lyndon B. Johnson's State of the Union, before publishing "Kennedy," the 1965 biography.
He stayed active in politics, campaigning for Robert F. Kennedy, then later joining the New York law firm Paul, Weiss, Rifkind, Wharton & Garrison, where he still works today.
"I think the television era has been hard on eloquence," said Sorensen. "Most politicians think that talking like JFK sounds old-fashioned today. And we have a president who doesn't round out the "ings" at the end of his words."
Like Kennedy, Sorensen retains a keen wit.
Bill Clinton was a great communicator, he said, but the one sentence best remembered is, "I did not have sexual relations with that woman."
"His mind is as sharp as ever," said Russell Riley, presidential scholar at the University of Virginia's Miller Center of Public Affairs. "I think it's an understatement to call him a mere speechwriter."
Indeed, Sorensen helped guide foreign policy.
He was part of the inner circle of advisers who for six days agonized over how to respond to the threat when U2 planes spotted Soviet missiles 90 miles off the Florida coast in Cuba.
Kennedy even entrusted Sorensen to deliver a "back door" message to Khrushchev, meeting a KGB courier on a Washington, D.C., street corner and exchanging a newspaper that contained an important message for the president.
But it is Sorensen's role as a writer -- reflected in the Kennedy speeches -- that still resonates.
"It's such a change from the current president who has only of late indicated that he has an interest in books," said Riley. "[Bush's] 2000 campaign practically made a virtue out of the fact he was uninterested in the written word."
As for Obama, "It's not just the words," said Riley, "but the person saying the words, with his youthful vigor and enthusiasm and his ability to impart that to the crowds."
Still, Riley struggles to understand how Obama has catapulted himself to the national stage.
In 2004, when Obama gave the convention speech, Riley was overseas and missed what he called the candidate's "coming out party."