Recall the mind-teaser: If you take an old ax, replace the handle, and then replace the blade, is it still the same ax?

Such a riddle confronted a crowd of Yorktown High School alumni on Saturday when they returned to their Arlington campus a half-century after graduation to size up a spanking new building—with nary a brick left from the edifice they grew up in.

I was on hand at my alma mater to observe several dozen of Yorktown’s “founders” reacting to this unusual dose of proof that time marches on.

Members of the original gangster classes from 1962-64, in town for reunion parties at the Key Bridge Marriott, can lay special claim to the Yorktown heritage. It was they who chose the school colors (Carolina blue and white), designed the class ring, nicknamed themselves Patriots, named the yearbook the Grenadier and christened the newspaper the Sentry.

Their choices were faithful to themes from the 1781 Battle of Yorktown, in which our French allies were instrumental in defeating the British. Inclusion of the fleur-de-lis on the school insignia was hotly debated, the alums recalled, and they were pleased to see it continue in the school’s 21st-century incarnation.

“I’m pleased to see the colors restored throughout the school,” said my friend Melody Miller, ’63, as she marveled at the fruits of the two-phase, five-year $103 million construction feat. “It’s a magnificent modern building with high-tech big-screen TVs that even tell you what the guidance counselors are doing,” she said. “It made me want to be in high school again, but then I thought about the SATs.”

Miller, with whom I’ve worked on the Yorktown Hall of Fame (temporarily disassembled due to construction), said the joined founders classes “retain a visceral loyalty that later classes don’t quite feel.” She recalled with pride Yorktown’s stature among the then-newly constructed North Arlington subdivisions as birthplace of WETA and a “show school” for visiting foreign diplomats.

Her fellow alums, in their latter sixties and enjoying retirement, arrived with their vintage school portraits on reunion name tags. One woman wore a ’62 letter sweater bedecked with awards for football, basketball and track earned by her husband, Bob “Moose” Ellis, a hero of that first gridiron victory over rival Washington-Lee.

Some expressed shock at the new structure, with its green attributes and post-9/11 security features. Jane Frisa from Lynchburg, Va., said she had attended elementary school at the old Greenbrier building that for decades was a wing of the high school but is now a parking lot.

Joel Hamaker, who settled not so far in Bethesda, Md., said he’d had no idea of the changes until he recently got a hint using Google maps.

Woody Greenwood from Washington State said he was having difficulty reimagining the layout of the old Yorktown, recalling a parking lot where he once got in trouble for starting a scooter drag race.

Most returnees looked on wide-eyed as they split into three groups for tours led by three current Yorktown student volunteers from the National Honor Society. “There’s nothing left of the old building, and some lockers were sold off,” they were told.

These guides, all seniors, professed little recollection themselves of the vanished original building. “It’s weird imagining coming back to see this one in 50 years,” said Jacqueline Verrecchia.

The ax has been passed. 

Charlie Clark may be e-mailed at cclarkjedd@aol.com