A roomful of students stares at the teacher as he pitches boldly into an explanation of a knotty new concept.

So it goes, sometimes day after day.

Then, it happens: scales fall from the eyes, light dances in the retinas, a chain reaction starts that puffs the blaze from brain to brain.

Comprehension. Understanding. They got it.

It’s the “aha” moment, the holy grail of teaching.

And not so many years ago, the deep satisfaction and joy Coast Guard Lt. James Diebag felt teaching adult education programs whispered something into his ear: “You could retire from the service and teach kids.”

So he did.

This month the first-year teacher welcomed his first students into his first science classes at Rainier Middle School, into a room decorated with a dangling sun, dangling planets, fascinating rocks and a thousand other subjects of future inquiry.

“It’s being at the introductory level of concepts for kids and you get the aha moment, and you go ‘bingo’ there’s the lightbulb, ‘now I see, now I understand, now I get it.’

“I love that process. It’s contagious. It’s neat to be there at that moment,” Diebag said.

A southeast Alaska native, Diebag attended high school in Darrington and returned to Alaska every summer to work on fishing boats.

He attended Central Washington University for a year, met Mindy Fugate of Auburn there, got married, and at 20 joined the U.S. Coast Guard. Ten physical moves in his 20-year career took him to most of the states. He started out at the bottom of the enlisted chain and worked up to E7 in the medical profession.

During his tour in Washington D.C., Diebag earned his graduate degree and bachelor of science from George Washington University. He became a warrant officer and taught science and health care before retiring from the service in 2007 as a lieutenant. The couple settled in his wife’s hometown. They have two sons, ages 17 and 19.

Diebag’s driving ambition upon his retirement, he said, was “to guide youth in their exploration of life.” With that in mind, he became a scoutmaster and coached soccer and baseball.

“I also substituted in the Auburn School District for a bit,” Diebag said. “What I realized was that, even though I had the skill set and the ability, I didn’t have the tools to teach in a public education setting, especially for middle school and to understand some of the students’ needs and how to meet those needs.”

He returned to school, earning his education degree and picking up his science credentials from the University of Washington Tacoma.

“I had the career in in depth science and chemistry and physiology and so forth in my career, but now it’s more of a hobby versus a career,” Diebag said of teaching science.

His fondest hope as a teacher, he said, is that “every student that comes through Mr. D’s class remembers that ‘Mr. D liked to let me get my hands into it, touch it, feel it, and experiment with it.’ I am someone one who believes you have to have a certain amount of academic work, reading, writing, but the fun of science is the availability of getting your hands on what you’re studying and working with.

“Of course, I also hope they have a lot of fun. That’s the goal,” Diebag said.