Over the years, students at Dumbarton Middle School, in Towson, have sometimes asked math teacher Tony DiStefano, 60, why he's so rarely out sick.

DiStefano has always told them he does stay home sick — but his identical twin serves as a substitute, making it seem like he's always there.

"His name is Michael," DiStefano said, laughing out loud.

Observant students notice that on certain days, DiStefano will flub their names when he calls on them. That's when Michael is subbing, DiStefano said.

If students still don't believe he has a twin, DiStefano shows them a photo from his daughter's wedding, clearly showing two men in the wedding party with DiStefano's face.

Paris Randall, a graduating eighth-grader at Dumbarton Middle, believes the story. Her classmate Logan Smith doesn't, but she doesn't blame Paris for believing.

"They seem pretty real," Logan said of DiStefano's stories.

DiStefano's stories might circulate for years to come, but he's done telling them. Last week he officially retired after teaching math in Baltimore County Public Schools for 36 years.

"He's a master teacher — there's no other way to say it," said Matt Kwiatkowski, chairman of the school's math department. "The kids come out of his class ready for the next level."

This is DiStefano's second attempt at retirement. His first effort was in 2005.

"After 30 years, I was just fed up with the piling up of non-teaching duties — they always add, they never subtract," he said.

The school administration, however, asked him to stick around part-time, and DiStefano agreed. He had been teaching Algebra I ever since. It's his favorite class to teach.

"You get to introduce how to be a math student in that course," DiStefano said.

A passion for teaching is one of the reasons DiStefano never accepted offers to become head of the math department.

"You teach fewer classes as an administrator," he said. "More than that, it was the administrative tasks I didn't want."

In short, he became a teacher because he wanted to teach.

Humor, hard-to-believe stories and the personal anecdotes that DiStefano is well-known for are only a means of building relationships with students and to be a better teacher, Kwiatkowski said.

It's about "breaking down those barriers that keep people from succeeding in math," he said.

It seems to work.

"He treats us more like a person than a student," Logan said. "He's nicer and more down-to-earth than other teachers."

Though he'll be retired, DiStefano's stories will continue to float around.

"I live in the neighborhood, and two of my neighbors had him (as a teacher) and still remember the stories, and they're now in their 40s," Kwiatkowski said.

"All the antics are just there to make it fun," DiStefano said. "Ninety-nine percent of the time, I'm teaching algebra."

The students are, apparently, learning both the algebra and its importance.

"Math is almost in every career," said Logan, a Towson resident.

Even if your job is to fill potholes?

"You need to know the area of the pothole," said Justin DeBouver, another graduating eighth-grader.

The students feel they've had the right teacher. Maybe it's the Force.

"Before each test, I have a good luck ceremony," DiStefano said.

He brings in a light saber and waves it over the students.

"May the Force be with you," he tells the students, who respond, "We accept the power of the Force."

It makes the students laugh, DiStefano said, "but it makes them relax before the test."

DiStefano always knew he wanted to teach. His brother, his favorite uncle and some of his cousins were teachers.

"I always looked up to teachers," he said. "You see good ones and you see bad ones, and I thought I could be a good one."

Also, DiStefano thought that working with kids would be a good way to make a living. It turned out he was right, and he's learned a thing or two over the years.

"I learned that most, if not all, of the trends that have come along don't work, such as kids teaching kids in groups," DiStefano said. "I was much more effective teaching my class the way a traditional, old-time teaching taught.

What has changed is how he relates to the students.

"When I started, all the role models of my family felt that you had to be strict. They used to say 'Don't smile till Christmas,' " he said. "Instead, I used humor and showed them respect, but respect was a two-way street."

The results have been remarkable.

"I have rarely, rarely, had a discipline problem," DiStefano said.

Some students, however, do struggle with algebra.

This year, he had a girl who had a lot of trouble. Midway through the third quarter, she started to get it to get it together.

Now, "She's a solid A-student," he said. "When you see a student take off like that, it's very rewarding."

The students appreciate it as well. At home, DiStefano has dozens of notes, cards and letters from former students and parents, thanking him for helping them. DiStefano still tears up reading some of them.

One, on pink-bordered stationary, was hand-written from a college student, saying she never would have made it through calculus class if DiStefano hadn't taught her how to study mathematics.

And yet he's leaving.

"I'll miss the kids, I just won't miss the testing and the emphasis on testing," DiStefano said. "After 36 years, it's time."

DiStefano says he and his wife, Barbara, enjoy hiking and reading, and they'd like to have more time to spend with family, especially if any of their three daughters were to have children.

"Our dream is about family — we're living our dream."

Of retirement, his plan is to have no plan, he said.

Then he added one thing.

"I think I'll tutor."