Iantha McMahon, Former East Hampton High School Algebra Teacher, Turns 100

Iantha Edwards McMahon, a former East Hampton High School teacher, was set to celebrate her 100th birthday on Wednesday, March 13, with her family in Palm City, Florida. Speaking by phone as she sat at the kitchen table with her three children, Kathy, Keith and Harold, on Tuesday, she said she planned to enjoy dinner and cake with family and close friends at home in Florida.

Ms. McMahon graduated from Cornell University in 1940. She was an algebra teacher at East Hampton High School from 1960 until 1976, and before that she taught at Pierson High School in Sag Harbor from 1941 to 1944.

In between, she was busy raising her three children. Now, Ms. McMahon has seven grandchildren and 10 great-grandchildren.

The Edwards family has roots in East Hampton that date back to the 1650s.

“I had a very good relationship with all of my students,” Ms. McMahon said over the phone on Tuesday. “I had so many wonderful students, and all of those who struggled got through.”

Some of her students said they knew her to be strict—but that she got the job done.

Deborah Mansir, who is now a programs coordinator at the high school, bubbled with appreciation for Ms. McMahon on Monday.

“Iantha McMahon was, hands down, the best and most dedicated teacher I ever had,” she said. “She set the bar and expectations high.”

If a student had trouble with homework, Ms. McMahon wanted them to call her at home. Ms. Mansir explained that her former teacher started her day at 6:30 a.m., to provide extra help for students right before the buses pulled in and the school bell rang for first period. She would often stay until 5 p.m. to provide after-school help.

“The year I had her for algebra, every one of her students passed the Algebra Regents, even if they had struggled all year, like me,” Ms. Mansir recalled. “She is an amazing woman who shines like a beacon in my memories.”

Former East Hampton Town Supervisor Larry Cantwell shared similar sentiments about Ms. McMahon, who taught him algebra in 1966. He said he remembered her students always having the highest scores on the New York State Algebra Regents.

“Mrs. McMahon was the best teacher I ever had,” he said on Monday. “She was always available before and after school and even at her home in the evenings. There was never an excuse for not finishing your algebra homework.”

Ms. McMahon mentioned that she had received a handwritten letter from Mr. Cantwell this week, as well as ones from several other students.

At first, she was just a substitute teacher at the high school. Then she received a call from the principal asking her to substitute for a teacher on maternity leave.

“I went in to sub and stayed there for 16 years,” she joked this week. “I loved being a teacher. I loved my students. I showed them respect and dedication.”

Her son, Harold McMahon, remembered that on some Saturday mornings, he’d go down to the kitchen and it would be full of kids doing math work with his mother. She’d have students over before the Regents to study in their Amagansett backyard also.

“She showed her students that it took diligence, hard work and perseverance,” he said. “She’s a phenomenal woman and role model. I had the fortune of being her son.”

Students and high school administrators gave Ms. McMahon a standing ovation when she visited the school a couple of years ago, said Mr. McMahon. “They said, ‘Mrs. McMahon is in the building: No chewing gum—and tuck your shirt in!’” he laughed.

“What gives her pride is knowing that there are students 40 or so years later who still write her notes,” her son said.

“I want to celebrate with my family and friends,” Ms. McMahon said the day before her birthday. “I’ve had a perfect life, a perfect husband and perfect kids.”