There are no erasers in David Acheson's classroom.

The Country School art teacher cuts them off because, he says, working without erasers can help young artists express themselves.

"I just tear them off," David says. "Children become perfectionists when they're not ready to be. That's okay sometimes, but not when you're drawing. That line you're about to erase may be useful five minutes from now...You short-circuit the whole process by taking away those lines."

With bachelor's and master's degrees in fine arts from Yale University, David is a professional sculptor who taught at Choate Rosemary Hall earlier in his career.

Now approaching the close of his 20th year at The Country School (TCS), David says two decades at the Madison school "was easy. I don't think of it as an achievement…I love what I do. I never dreamt it could be so fulfilling."

That may be because David's classroom is an easy place to be, where the pencils have no erasers and students are free to color outside the proverbial lines.

"I give them permission to make mistakes," says David, who arrived at TCS in the fall of 1991. "I am not opposed to letting people make a terrible error, but I'm there to pick up the pieces and to make sure they get something out of that mistake, so that it's not a bad day and they don't walk away thinking they failed. They didn't fail at all. They just learned something."

With a lighthearted approach that has David chuckling at the memory of allowing a student to take apart his stapler, which never worked again, and unorthodox assignments that include tearing up the masterworks, David says the means is sometimes more important than the end.

"What we do in here is not about product. I'm more interested in a child understanding what creating is all about. It's about the process and not getting in the way of that as it happens," he says.

The process in David's class includes looking at art as well as making it. David chaperones several student field trips every year to the Museum of Modern Art, the Rhode Island School of Design, and the Florence Griswold Museum, most recently accompanying a 3rd-grade group to the Yale Center for British Art.

"David Acheson is a real treasure," says Head of School Laurie Bottiger. "For 20 years, he has been guiding students as they explore and then create innovative solutions. He is our 'art' teacher, but everything he does touches on other disciplines, so it's no surprise that some of his former students are inventors and scientists as well as artists."

In fact, several former students have gone on to careers in the arts, including artist Jared Madere, photographer Adrien Broome, fashion designer Rebecca Joslow, costume designer Katie Hartsoe, and art teacher Rebecca Figler.

This March, David brought a retrospective of student artwork to the Community Room at Madison's Scranton Library and plans another such show for 2013. As advisor to the student set design club for the length of his tenure at TCS, he has worked with students and parent volunteers to build sets from scratch for school plays, most recently on Beauty and the Beast. Just like everything else in David's class, the designs are "always open to change," he says, adding that sets often end up looking very different from initial blueprints.

Another pet project is the spring's Pond Yacht Regatta, when David floods the campus's four-square court, turning it into a pond in which students race self-designed boats. According to David, however, the competition is a contest in name and isn't about winning at all.

"I would use 'contest' very loosely. Everyone wins. It's just a wonderful, wonderful time."

Hearing about his students' successes makes David "feel great," he says. "That's what I wanted to do when I started teaching. I wanted to make a difference."

But he adds that it's just as gratifying for him as a teacher "when someone who doesn't have a lot of innate talent, but really did make the effort can sit down and do an observational drawing as well as anyone can."

One student who will be sorry to leave David's classroom when she graduates this spring is 8th-grader Katelin Gochberg, 14, of Killingworth.

"I love his class," Katelin says. "Mr. A taught me how to paint, how to draw, and to think that something might not be perfect, but that's art and that's the way it should be. One of my favorite things was when I was drawing a face and the eye was over there and he said, 'That's okay.'"