Frank Harris is explaining a diagram to his first-period statistics class at Edward M. Kennedy Academy for Health Careers when a boy in the back interrupts to repeat a word Harris said.

“Pattern?’’ the student asks.

“Pattehn,’’ Harris responds.

Then he chuckles, realizing the student is teasing him about his accent.

“That’s just old-school Dahchestah, y’know,’’ says a smiling Harris.

His easygoing and supportive relationship with students has helped place Harris, 59, among five finalists for a national award that honors everyday heroes in the classroom, given annually to educators who show deep dedication and compassion for students.

Students and colleagues say Harris, who came to teaching through a mid-life career change, is the kind of teacher who takes time for every student and notices those who might otherwise be passed over.

In this Thursday morning class, Harris frequently connects lessons with stories from his life or with Boston-area issues.

When he discusses polio vaccine trials, he recalls his mother’s long-ago fears that overexertion could contribute to polio, leading her to call him inside for afternoon naps on hot days.

Describing a study of manatees killed by powerboats in Florida, he relates it to dangers that seals and whales face in Boston Harbor.

When he asks students to construct a study on the effects of caffeine, he laments giving up regular coffee.

“Decaf is the worst,’’ he says.

After class, Harris says he looks for ways to relate to his students, almost all black or Latino, and to show that their white teacher has shared some of their experiences growing up in the city.

“I can still be a role model in my own way,’’ he says.

His students say Harris just gets it.

“He knows how to talk to students, and he relates to what their difficulties may be,’’ says Stacia Aguirre, 17, of Dorchester. “He’s understanding. . . . I’m comfortable with him.’’

Andrew Burton Edge, 19, also of Dorchester, says he won the school’s science fair with help from Harris, who holds him to the same high standard as all his students, though Edge is dyslexic.

“He’s one of those teachers that genuinely cares about his students; he wants all his students to pass,’’ he says. “He does whatever it takes. If you have an attendance problem . . . if math just may not be your thing, he helps you out, and he gives you the individual attention that you need.’’

Harris grew up in Dorchester and since 1980 has lived with his wife in her hometown of Winthrop, where they raised two sons, Kevin and Sean.

He became a teacher in 1998, after a career as a consultant to small businesses. His work automating the accounting system for the Chinese restaurant chain Weylu’s led to a stint in the late 1980s as its chief financial officer, he says, and he first came to Kennedy Academy to help with its computer system.

You could say he was just entering the family business. His father was also a teacher who entered the profession in mid-life, after working for years as a welder and pipefitter at Boston Navy Yard.

Two of Harris’s brothers are current or former teachers, and a sister is a school psychologist. His wife teaches special-needs children in Everett, and his late mother-in-law was a business teacher in Revere.

“I knew it was a rewarding job, and I also knew the work that I was going to have to do, because I could see my father had to go back to school. . . . I went into it with my eyes wide open,’’ he says.

Kimberly Frazier-Booth, a Kennedy Academy English teacher who nominated Harris for the award, sponsored by the American Federation of Teachers, says every teacher in the small school takes on extra responsibilities, but Harris is impressive in the variety of roles he has embraced and his longstanding dedication to them.

“This is somebody that brings it 100 percent, every single day,’’ she says.

Harris insists he is just part of a dedicated team. He credits the persuasive power of Frazier-Booth’s nomination letter for making him a finalist for the award.

“I love what I do, I love where I work, and I love the people I work with,’’ he says. “I’m pretty lucky.’’

Online voting for the award closes at midnight Sunday.

Jeremy C. Fox can be reached at jeremy.fox@globe.com. Follow him on Twitter @jeremycfox.