A ninja warrior can be anything from a medieval Japanese fighter to a cartoon group of 21st-century mutant turtles combatting evil.

At Chester Elementary School, the ninjas are something else entirely: Kindness Ninjas, part of a program of special activities the school organizes for two six-week periods during the year. Among the other programs, all of which meet one time a week, are a school newspaper, a chess club, and an engineering activity featuring 3D printing.

The Kindness Ninjas were the inspiration of fifth-grade teacher Andrea Selmer. Every Friday for six weeks, the 13 students in grades four to six get to school early, put on their Kindness Ninjas t-shirts, and greet incoming busses with waves, smiles, and signs they have made that say things like Happy Fri-yay, Make a Difference and, of course, Be Kind.

And the Friday greetings happen to musical accompaniment.

“We play fun music, upbeat, something like Don’t Worry Be Happy,” Andrea says.

Kindness Ninjas have other activities. They make smiley faces, which they hide around the school, tucking them in places like the edge of a bulletin board. Each has a cheerful message, things like Be a Star or Spread Joy Around. Andrea says often, the student who finds the smiley face will pass on the message by hiding the sticker again.

The Kindness Ninja students also make decorations for classroom doors, large pieces of butcher paper with positive messages. The school nurse, for instance, got a door poster that read, “Thank you for healing our troubles away,” and a new one for a kindergarten teacher, scheduled to go up this month, reads, “Thanks for a great start.” There are no rules about how long the door decoration can stay up. One cheerful message from last year is still on a classroom door.

The Kindness Ninjas do not forget teachers. Andrea bought a plate, which was then filled with surprise, home-baked goods that she contributed. The students, using a randomizing computer program, selected the name of a Chester Elementary teacher to receive the surprise plate. The teacher who receives the surprise plate then passes it on to another member of the school staff with a new surprise of that teacher’s own choosing.

This is Andrea’s third year as a teacher, all at Chester Elementary. The school, however, was not new to her. She had worked for the previous eight years as a para-educator.

“I’m a bit long in the tooth to be starting,” she admits.

Three years ago, when there was a teaching position open, Andrea felt the time was right to apply for the job. Her children were teenagers. She had more time to devote to a demanding career.

“It was the timing; I couldn’t say no; I couldn’t let it slip by; I know this is what I was meant to do,” she says.

Andrea, who describes herself as “an extroverted introvert,” sees age and the wisdom it brings as an advantage in her new career as a classroom teacher.

“I have life experience and the enthusiasm of a young teacher,” she says. “I wouldn’t want to teach if I couldn’t give it my all.”

She co-teaches with Chester Elementary’s other fifth-grade instructor, Amy Lippincott. Each has her own classroom, but the students move around. Andrea does all the fifth grade math instruction; her co-teacher does the reading.

Andrea, then Andrea Komatz, grew up in Clinton and graduated from Morgan High School and Eastern Connecticut State University, where she met her husband, Jay. She notes that her maiden name, Komatz, was the subject of much creative mispronunciation.

“You can only imagine the ways in which my peers liked to change it,” she says.

She had planned on a career in journalism when she started college, but by the end of her sophomore year, she knew it was not right for her and changed her major to education.

One of her own college experiences underlined for her the importance of a kind gesture. Her mother loved the books of best-selling author Wally Lamb, who then lived in Willimantic, where Eastern is located. She looked him up in the telephone book, found a number, and called. When she asked if he would sign a book for her mother, he told her to come over, and he did just that.

Beyond her teaching, Andrea is a faithful player of the popular word game Wordle. She describes herself as “not too bad.” Usually, she gets the word in four guesses. She likes true crime documentaries and podcasts.

“True crime is so far from my reality that I find it fascinating,” she explains. “I like watching a case unfold and be solved.”

Kindness Ninjas greets students on Friday mornings, but to make sure kindness is an everyday occurrence at Chester Elementary, the students in the group have set up what they call an affirmation station in the school’s hallway.

Anyone can come up and take a slip of paper with a message of good cheer. On a recent afternoon, this reporter took advantage of the opportunity. The affirmation station message read: I chose to speak kind words to myself and others every day.

What could be better advice?