After the author's death in 2007 at 83, Tripoli wrote a post about him on the cemetery's website. That tribute inspired John Palmer, the former director at Arlington, to ask if Tripoli would help the cemetery prepare a presentation for local students. Thus was born a series of field trips.
Earlier this month, four groups of sixth graders at Drexel Hill Middle School gathered in the cemetery's chapel to listen to Tripoli - assisted by son Michael, now a 17-year-old junior at Penn Ridge High School - give a short presentation about Alexander, creativity, and imagination.
Alexander is the author of the five-volume Chronicles of Prydain series, The Westmark Trilogy (whose first volume won a National Book Award), Time Cat, and dozens of children's books, biographies, and novels. The 1985 Disney animated movie The Black Cauldron was based on his work.
As a child, Alexander was not much of a student, as Tripoli tells it, though he was reading at 4, skipped two grades in school, and graduated from Upper Darby High at age 16. He told his nonreader parents he wanted to write books. They suggested he get a real job.
After a semester at Haverford College, Alexander joined the Army and fought in World War II. Along the way he taught himself French, visited Wales - where he ate up Welsh mythology - and met his future wife, Janine, in France.
For a long while after returning home, he wrote books for adult readers, with limited success. It was only when he turned to children's fantasy literature, with 1963's Time Cat, that his career took off.
As Tripoli told Alexander's story, some students scribbled the names of his books on their hands.
Rachael Fulmer, a teacher with the group, said she plans to buy some of Alexander's books for her classroom library. They are not part of the state's core curriculum, but she wants to make sure they are available to students, she said.
"I never knew there was so much history in Drexel Hill," she said.
"It is a great opportunity for the students," said Gary Buss, president and chief executive of Arlington Cemetery. "It helps keep the memory and mission of Lloyd Alexander alive."
Alexander died just a few weeks after his wife of 61 years. Their urns - in the shape of books - rest side by side behind glass in the cemetery's mausoleum, the next stop on the field-trip tour.
Darren Boyce, 12, has read a few books from The Chronicles of Prydain. "This has made me like his books," he said.
Nate Polidoro, 11, also a fan of Alexander's, called the lecture "very informative" and something he had not heard before.
"They are the kind of books that once you start reading it you get hooked because the books are so fun," he said.
Tripoli, who works at GlaxoSmithKline, has done the presentations as a "labor of love," he said. "To me the big thing is inspiring those kids."
Lloyd Alexander once said, "Fantasy is hardly an escape from reality. It is a way of understanding it."