He dashes curse words in the classroom. He beats students with a shovel. And students love him. What's the secret here?

Woo Hyung-chul, 46, teaches math at a private institution or hakwon in Seoul that prepares students to get into colleges.

There are many teachers like him in Korea where education is a religion. But Woo stands out among them because his pedagogical approach is different.

"Don't throw an unrealizable goal to students on the first day." That's one of the lessons he shares in an interview with Donga Ilbo on Saturday. "Students will find it beyond their reach and give up."

Most of Woo's students are "problem kids" by some definition. They don't do well academically. Their attention span is short. But when they come to Yoo, their grades improve. If not, they at least have a good time laughing a lot. And as days go by, these students' grades also tend to pick up eventually. So, he's special.

Woo believes that when students don't do well academically, it's partly the teachers' fault. "You need to understand the teen culture to motivate them. When you motivate them, they do better academically," he said.

The secret of his approach lies in his three-step formula of "first apply sticks, then carrots, and show a vision."

He prepares his lecture by watching a comedy program. He uses the jokes he picked up from the comedy show in "disarming students and opening their hearts." He also uses "shock and awe" strategy. This includes intentionally cursing them and an exaggerated gesture of beating them with a shovel.

If it were in the U.S., he would be probably in jail for doing so. But yeah, it's Korea.

The chemistry he creates with such non-conventional methods is formidably effective and his income proves it. Students who gave up on math call him a "messiah" for redeeming them from the deep, dark valley of hopelessness and a state of utter lack of motivation.

Being a good deliverer of knowledge isn't enough, he says. "Students are not a memorizing machine. You should guide them to help find a life goal by meeting them on their terms," he said. "Creating a common ground of understanding between you and students is critical."