Jack Hopkins, 97, shows off a few of the harmonicas in the collection he’s built up over nine decades. Hopkins isn’t sure exactly how many of the harps he owns but says he has at least 15 different kinds. (Jonathan Hunley for The Washington Post)

The preschooler had a question for the visiting musician: When you play the harmonica, how can you see the holes you use to make sounds?

You can’t, Jack Hopkins told the boy, because your mouth is covering them. That makes it more difficult to play, in some ways, than other instruments.

“The violin, you can see where your fingers are,” Hopkins said last week at Lake Ridge Baptist Church’s preschool. “The trumpet, you can see where your fingers are.”

Hopkins seems to have moved past that challenge; he’s been playing the harmonica for more than nine decades. At 97, he’s also still singing at church and with the New Dominion Choraliers community choir, as well as sharing his love of music with others — such as the preschoolers at Lake Ridge Baptist.

The harmonica adventures began for Hopkins when he was growing up in Upstate New York. He received a plastic toy harp in his Christmas stocking when he was 5 or 6 years old.

Hopkins discovered he could play a musical scale on the harmonica, and he figured if he could do that, he should be able to learn a song.

“So my father came home from work a few weeks later, heard me playing a popular tune of the day, and it blew his mind because he had no more musical talent than your cellphone has,” Hopkins said in an interview a day before his trip to see the preschool students.

Hopkins, who has lived at the Westminster at Lake Ridge retirement community for 17 years, said he’s not sure how many harmonicas he owns, although his collection includes at least 15 different types. He has harmonicas that are 1½ inches long, and a chord harmonica that measures just shy of two feet.

He even has a sextet harmonica that resembles the paddle wheel on a riverboat. It’s technically six harps hooked together, with small handles on each side so a player can spin from one harmonica to the next.

Hopkins said he likes the harmonica because it’s generally made in a convenient size — he had two of the smallest ones on a chain around his neck last week — and because its tones can express emotions.

He played it at the Kennedy Center once, with the opera house orchestra (although he recalled that his wife, Beth, now deceased, couldn’t pick his part out from the other musicians’), and he’s performed in nonprofessional settings.

Don Spellmann, who sings with Hopkins in the New Dominion Choraliers, recalled his friend bringing a special touch to Spellmann’s wedding reception in August, when Hopkins treated the crowd to impromptu harp stylings.

Hopkins just always seems to have a positive air about him, Spellmann said.

“We all kind of want to grow up to be Jack,” he added.

Hopkins also plays the harmonica along with each hymn every Sunday at his church, Bethel United Methodist in Woodbridge.

He sings in the choir, too, and his tenor voice is good, and not just for a man in his late 90s, said church music director Joe Swetnam.

“It would be good for any age,” said Swetnam, who also performs with Hopkins in the New Dominion Choraliers.

Jenny Struck, who teaches at Lake Ridge Baptist’s preschool, said she appreciates that Hopkins is willing to share his talent with children. She met him two years ago and invited him to speak at another preschool where she worked.

“You know, at 97, he has so much energy and is just engaging with the children,” Struck said.

Hopkins would have had a full life even if he hadn’t been into music. The World War II veteran has seven children and seven grandchildren. He also worked for the Army as a civilian, and he is a retired mechanical engineer.

He doesn’t drive anymore, and he said he doesn’t walk as far or as fast as he once did.

But other than that, he’s healthy. He’s not sure what to attribute his long life to, but he said he agrees with other harmonica aficionados that the breathing in and out that’s required to play the instrument is good for the lungs.

Hopkins also tries to drink water frequently and get lots of sleep.

“And I buy carrots by the pound and eat them raw,” he said.