When Marybeth Hearn was 10 years old, she asked her parents to let her train a puppy to become a guide dog. It turned into a lifelong mission.

Over more than five decades, Hearn has raised 56 dogs to assist visually impaired people. But her legacy doesn’t end there — the recently retired, longtime high school teacher has inspired several of her family members and dozens of students to train many more.

“I like doing something good for somebody I just haven’t had the chance to meet yet,” said Hearn, who on December 18 ended 33 years of teaching agriculture at Lemoore High School in California’s San Joaquin Valley.

When she approached her parents decades ago, prospects seemed unlikely. Her mom didn’t like dogs, and her dad doubted she would be able to find a sponsor to pay for the cost of the training.

Hearn was so determined, however, that she presented the project at a Lions Club and raised $2,500. So on a sunny summer day in 1962, the family drove home with a black Lab named Letta barking on the back seat, the first of a long series of puppy trainees.

Two sons and a granddaughter have followed in Hearn’s footsteps, but her greatest impact has come from mentoring a generation of student trainers, who since 1992 have worked through a school club with 170 dogs that ended up in a variety of service posts.

They spend 14 months with each puppy teaching them skills, such as house-training, walking with a leash and behaving well in public. The dogs live full-time with the students, attending their classes and field trips to become socialized.

“If you can imagine a classroom with 21 [months-old] puppies and 30 kids, it’s quite the extravaganza,” Hearn said.

The dogs then move to trainers employed by Guide Dogs for the Blind, a nonprofit organization that partners with the program, before graduating and being paired with two-legged companions. Those that aren’t up to the difficult task of assisting the blind can become other kinds of service animals.

Often students attend the graduations and help ceremonially pass the dogs on.

“I love to see the look on the kids’ faces . . . when they get to see that dog again after three or four months and the dog remembers them,” Hearn said. “It’s a great feeling.”

After classes went virtual at Lemoore in March because of the coronavirus pandemic, the program continued and has since trained 12 puppies.

Students came to the school for what Hearn called “socially distanced play dates” in the fields, with everyone wearing masks and six feet apart and puppies “running all over the place with their toys.”

“It was great, because it gave the kids a way to communicate with each other and not be so completely isolated,” she said.

Christine Benninger, Guide Dogs for the Blind’s president, said Hearn’s work has had a “tremendous positive impact” on the organization, which graduates about 300 dogs each year to play a role that has become more vital this year.

“Blindness isolates you to begin with, and now with covid we’re even more isolated,” Benninger said. “So just for one’s mental health or companionship, having a reason to get up and go somewhere every day, having a guide dog is lifesaving for some of our clients.”