Students say he is the hardest math teacher, possibly the hardest teacher on campus.

Some students walk through his door on the first day fearful of the year. In fact, his supposed strictness has become somewhat of an inside joke among students.

However, as the years go on, students are discovering that math teacher PJ Yim has a more humorous side.

On his wall are many posters that have amusing or motivational phrases. Many of them say “Be Like Cactus.” As it turns out, there’s an oft-repeated story with that phrase.

Yim had a girlfriend, and according to Yim, she was moody and upset all the time. During one of her unhappy moods, Yim bought her a cactus to cheer her up.

“Bringing your girlfriend a cactus is a very weird thing to do,” Yim said. “But I brought her a cactus because a cactus is resilient in a harsh environment and resourceful in times of scarcity. I wanted her to be like cactus.”

His girlfriend was not so appreciative of the gesture.

“She said, ‘Do I look like a cactus to you?’” Yim recalls with a laugh. “‘Am I really that ugly?’”
 
Yim then explained to her that the meaning of the cactus was not its physical appearance, but its inner qualities.

“No, I bought you a cactus instead of a rose because you’re going through a rough patch in your life, and I want you to be like cactus  strong even during times of drought,” Yim said. “I didn’t want to get you a rose because a rose would wither away.”

Yim said that he broke up with her shortly because he was sick of her negative attitude and her lack of appreciation of his gesture.

Other posters on his wall tell other stories. Another drawing, a pencil-drawn caricature of Yim as a fire-breathing dragon, is labeled “The Yim Dragon.”

“Ah, the ‘Yim Dragon.’ Some student several years ago drew me as a fire-breathing dragon on his homework. I confiscated it, thought it was pretty funny, and put it up on the wall,” Yim said.

However, Yim says that his stories are meant to teach something rather than to get laughs.

“I tell stories to make a point,” Yim said. “I’m not trying to be funny.”

Many of his stories teach key concepts. For example, he once told a story about struggling to read Shakespeare to illustrate the point that math is like Shakespeare: The language is complicated, but the core concept is simple and beautiful.

As for his perceived toughness, Yim says that most students believe that he is impossibly hard because of rumors and gossip. But no matter what people say, Yim’s humorous side shines through from behind his stern facade.

“I don’t smile,” Yim said. He takes a bite of a bologna sandwich and grins, “except when I’m eating.”