He then dissects the formula to the math problem, draws a pi symbol on the board and calls on students to help him out.
When the classroom seems to stumble, Struble tries humor to grab their interest.
"What kind of pi are we looking for? Apple, peach?" Struble says.
As a group, the class takes a couple of shots and eventually comes up with the right answer. He repeats the steps and makes sure everyone in the class understands before moving on the next problem.
"It's rewarding when a kid comes up to me and says, "Gee, I know how to do that now," Struble said. "It's rewarding to actually see them know something."
Struble, who has trained teachers in Sierra Leone as a member of the Peace Corps and taught in Oakland, N.J., and in Prince Georges County, Md., says his favorite place to teach is in Washington County Public Schools.
"Washington County is a very good school system," Struble said. "There's really a focus on learning."
He left his teaching position in Prince Georges County and came to Washington County without another job lined up. After substituting for a year, he landed a spot at Boonsboro Middle, where he has taught for the last nine years. He has 27 years teaching experience.
Struble said he walked away from his job in Prince Georges County because he felt there was a focus on keeping order in the classrooms rather than teaching.
"I simply left my job down there and hoped I could get a job down here," he said.
Struble likes to keep variety in his line of work by being a department chair and team leader at Boonsboro Middle. He's also spent a summer in Japan learning about that country's education system. He thinks those experiences will help keep his job fresh as well as provide personal enrichment.
"I look for an opportunity in the summer to do something unique and unusual," he said. "It's to help me learn about myself. I always say if they pay me, feed me and house me, I'll go."
Outside of education Struble is a member of the Gad-Abouts Square Dancing Club and dances every other Saturday night. He says that's also how he met his wife, Andrea. They have no children.
Struble said he and his wife are so into square dancing that they book vacations around national square dancing conventions.
The two are also members of the Victorian Society, where they wear replicas of old Victorian clothes to gatherings.
"Both of our hobbies include wearing silly clothes," he joked.
But while Struble has a wide array of interests, he doesn't boast any major accomplishments. He says his successes come from teaching, and it's still a job he looks forward to everyday. He has no plans to leave the field anytime soon.
"I really pride myself on being able to make math fun and interesting," Struble says. "I still have an enthusiasm for teaching. When it stops being fun, when it stops being rewarding, then that's when I'll walk away."