“Oh, I don’t know …” That’s the response physical education teacher Marsha Niemann often heard when she would encourage her Justin-Siena high school students or senior citizens to sign up for a month of multi-generational bowling.

But among those who gave the afternoon bowling sessions a chance, Wednesday afternoon’s abundance of high-fives and laughter left no doubt that participants, old and young alike, were having fun.

What started four years ago as a “service learning project” for Justin-Siena students to earn once-mandatory community service hours, has evolved into a voluntary and increasingly popular after-school activity, Niemann said.

The program, which draws senior citizens and high schoolers together once a week through January, felt and sounded more like a party than anything else Wednesday afternoon at Napa Bowl.

Jerry Shelton, 68, seemed to be amassing a small fan club as he bowled five, six, then seven strikes in a row. A few boys took up the chant “Jerry, Jerry!” after leaning in to give Shelton a high five.

Beyond sharing the highs and lows of the game, the Wednesday bowling sessions have given several participants the opportunity to befriend people from a different generation.

Kyle Johnsen, a 16-year-old junior, said plenty of times chats about bowling were a springboard for sharing life experiences.

“You realize a lot of them have done great things in their life,” Johnsen said.

He added that he’s learned: “Don’t judge a book by its cover. They’ll beat you at bowling. A lot of them are really young at heart.”

One thing everybody there shared in common, regardless of skill level, was a love for knocking down pins.

Shelton, who wore both a trophy watch and ring for hitting a bowl score of 300, said at first he thought the program involved mentoring a young bowler one on one, but when he arrived he discovered “just a bunch of nice people bowling.”

Still, Shelton has managed to occasionally impart some bowling know-how to the youngsters such as how to correctly throw the ball and how to approach the line before the throw, among other things.

“A lot of them don’t realize there’s a 30-foot oil spot (in the lane, just before the pins),” he said. “I tell them if you miss the oil spot, you’re not going to get a strike.”

Ryan Andre, a 16-year-old junior, said he can only hope that as a senior citizen he’s bowling like some of his elderly teammates.

“I think it’s amazing. There’s a 90-year-old woman who still bowls strikes and stuff. They’re a lot stronger than I thought,” said Andre, who added that thanks to the program he’s considering joining a competitive bowling league.

Other participants like Claire Woolf, a 17-year-old senior, don’t feel any competitive urge toward bowling, and come strictly for fun.

“You meet some really interesting people, a lot of war vets, and it’s nice to hear someone say they’ve been bowling with their friend for more than 30 years,” said Woolf, who’s in her second year with the bowling program.

“Everybody can do this sport. Not everybody can run a mile fast. But no matter how old you are you can always go bowling,” Woolf added.

As a novice bowler, Bonnie Cullen, 17, said she came out just for the entertainment value and ended up picking up a few bowling skills.

“They teach you a lot about bowling, especially when you don’t know anything about bowling like me,” Cullen said. “It’s fun for everyone. They’re really talkative. They know how to strike up a conversation about anything.”

Meanwhile, some high schoolers and seniors wish the month-long program lasted a little longer or ran twice a year.

Russell Davenport, a 66-year-old retired ship-fitter who used to work at Mare Island and coach kids in bowling and soccer, said it takes more than four sessions to pass on any lasting guidance.

Nonetheless, Davenport turned his attention to Cullen to gently advise her that when throwing the ball she needed to bend her knees.

“If you’re not getting down low enough, you can’t have any consistency,” he said, before adding with a smile, “The important thing is: It seems like they’re having fun.”