Even so, this was relatively good. Honestly, among the classes Juhan taught, there was no class this quiet.
Seo Juhan realized for the first time how gratifying it was that his voice wasn’t drowned out by noise.
“If you write it as an equation…”
Seo Juhan turned around to write on the board. Then he immediately realized he’d forgotten to bring the chalk holder from the classroom where he’d taught the previous class.
He examined the ledge below the blackboard. In the narrow crevice, he could see small broken pieces of chalk. They looked like scattered toys. In the end, he picked up a white one among those chalk stubs.
“If you expand tangent alpha plus pi over 4, it’s 1 minus tangent alpha times tangent pi over 4… but tangent pi over 4 is 1 anyway, so I won’t write it.”
Along with the explanation, the sound of chalk tapping echoed through the classroom.
The blackboard was hazy as if covered with white residue, but it wasn’t to the point where you couldn’t read what was written.
Seo Juhan, who was writing the equation, flinched when he saw graffiti marks. What remained like an afterimage even after being erased with an eraser was the shape of a woman’s breasts. However, he pretended not to notice and continued speaking.
“The numerator is tangent alpha plus 1. Since this value is given as 2, if you solve this, you can find tangent alpha. This is just mental math…”
Honestly, it was an equation that even upper elementary school students could probably calculate. For a class aimed at those preparing for college entrance exams, it should have been skipped.
“Never mind.”
But Seo Juhan kindly wrote it out.
“If you multiply both sides by the denominator, this side is 2 minus 2 tangent alpha, move this over and it’s 3 tangent, move this and it’s 1. So tangent alpha becomes one-third.”
There probably weren’t many listening anyway, but it was a courtesy to those kids who showed at least minimal respect for their homeroom teacher.
Seo Juhan, who had gone to the trouble of verbally explaining a problem that could be solved mentally, put down the chalk. Then he dusted off his powder-covered hands.
“Now try solving the practice problem next to it yourself.”
Seo Juhan clasped his hands behind his back and slowly started walking. He walked between the crooked desks like caterpillars and scanned the seated students.
What moved Seo Juhan was curiosity centered on interest rather than concern as a teacher.
At some point, he’d come to know the fun of observing the human crowd. It was the mindset of enjoying a sense of superiority while touring cages at a zoo.
The rough black heads were mostly busy looking at phones hidden in their desk drawers. Since they didn’t even think to put them away when Seo Juhan passed right by them, it was even ambiguous to say they were hiding them.
In any case, they were sitting in their seats.
The desks with math books placed haphazardly on them were almost all in terrible condition.
The corners were worn and broken as if poked with an awl. The flat surfaces were riddled with dirty graffiti. It seemed partly because they were old, but there was a high probability they’d been tormented by inconsiderate users.
Some had graphite marks remaining darkly. It made him wonder how they could look at that with their eyes open. It seemed like the eraser would turn pitch black the more you erased. Seo Juhan didn’t want to use them even if he scrubbed them hard with 99.9% antibacterial wet wipes.
How on earth did they make that hole? It definitely wasn’t there in March.
Some desks even had wide holes drilled through them. The dog hole carved out of thick plywood was perfect for looking at a phone screen. He was even impressed by the exquisite shape and size. Though he didn’t know which artisan’s work it was, it was like watching craftsmanship.
Can you cut that with a cutter knife? The precision is almost at the level of a chainsaw.
“Teacher.”
Seo Juhan, lost in fantasy, didn’t hear the call and walked leisurely between the desks.
“Teacher.”
“Huh? Oh, yeah.”
Only then did Seo Juhan hear someone calling him and turned around. Somehow it felt awkward because he heard “ssaem” more often than the title “teacher.”
Go Un lightly waved his hand holding a mechanical pencil as if to say he was the one who called.
The curtain fluttered gently at the edge of Go Un’s desk. Perhaps because it was a window seat, it had charm like watching a student drama. It was probably because of the plausible appearance of the only kid who wore his uniform properly.
Though he was still the same punk who rode around on a bike.
“What?”
Seo Juhan approached Go Un with large strides and asked.
“How do you solve this?”
Go Un tapped the book with the tip of his mechanical pencil. Though it was a small voice, it had a heavy resonance like a contrabass. It spread thoroughly to the corners of the classroom.
“Ah…”
Seo Juhan blinked as if he couldn’t understand what he’d just heard.
On Go Un’s desk was the college entrance exam prep book whose solution he’d just instructed them to work on. The alphabets and numbers written there seemed to be flying around, but it was clear they were some kind of solution.
Seo Juhan looked at those traces of effort unfamiliarly before belatedly asking.
“…Uh, yeah. Which problem?”
“This one.”
Go Un, who had been showing off the trick of spinning the mechanical pencil with his left hand, tapped the book again.
“Can I see your pencil?”
“Here.”
Seo Juhan received the end part of the mechanical pencil. Their bare skin briefly touched.
“Since it says to internally divide in a 3 to 1 ratio, let’s write this as 3k and this as k. Then since we need to find cosine of alpha minus beta, we just need to find cosine alpha and cosine beta.”
Seo Juhan explained gently while writing directly in the book.
Usually, students gave off a peculiar foul smell of cigarettes or mixed with sweat. When approaching closer than a certain distance, even the cologne defensive barrier was useless, so he desperately needed a gas mask.
But strangely, Go Un didn’t have that. A fresh fabric softener scent drifted. The distance that had been established by the bike alone melted away warmly.
“You learned the trigonometric function formula last time, right? Cosine alpha is three-fifths, and cosine beta is two over root five…”
Seo Juhan’s upper body, having regained stability, gradually tilted.
“Then sine alpha is four-fifths, sine beta is one over root five. If you multiply them together and add, it’s two root five over five. You get it now, right?”
Go Un raised and lowered his thick eyebrows.
“…No.”
Did I talk too fast?
“Look at it again.”
Seo Juhan grabbed the back of Go Un’s chair and bent down more.
“Since these are right triangles, if you find the length of the base, you can find the values of sine alpha and sine beta.”
Every time the mechanical pencil moved, Go Un’s sturdy shoulder touched Juhan’s stomach area slightly.
“Do you understand up to here?”
Go Un glanced up at Juhan’s profile and turned his gaze away.
“…I’m not really sure.”
Hmm. Seo Juhan stood on one leg and looked down at the round crown of his head.
How can he not understand even this?
During his school days, if someone didn’t understand even after such an explanation, he would have told them to go ask the teacher. But now that he was in the teacher’s position, he couldn’t pass it off to anyone.
“I’ll explain it again. Listen carefully.”
Seo Juhan bent his knees as if squatting to lower his eye level and started explaining again.
He thought of him as an elementary school student and used only easy-to-understand terms. Since he’d given up long ago anyway, he could lower his expectations infinitely.
Since there were no other students to whom he needed to divert his attention, he used all the energy he’d been saving. With the feeling of sculpting brain wrinkles, he devoted himself like a sculptor with passion.
“If you’re confused, write the formula like this first. Do you get it now?”
“Ah, yes. I understand now.”
Go Un, who had been listening attentively to the lengthy explanation, finally gave the okay sign.
“Good.”
Seo Juhan put the mechanical pencil down on the book with a tap. The pencil slid right in front of them and stopped where the book folded into a concave shape.
“Then try solving this one?”
Seo Juhan casually asked while pointing at another problem with his finger.
“It’s the same type, so let’s check if you properly understood.”
“…Yes.”
Go Un picked up the mechanical pencil with his left hand and worked through the problem with scratching sounds.
Seo Juhan waited silently beside him. Since he didn’t have to look after other students, he could afford to be relaxed.
It took a little time, but Go Un found the solution.
“Oh. Correct.”
Seo Juhan flipped backward through the pages and picked out one more problem.
“This time, this one too.”
“Yes.”
This time, the problem-solving speed was even faster.
“Wow, you’re doing well. Good.”
Seo Juhan, who was originally stingy with praise, didn’t realize how generous he’d become.
I think this is enough now.
“Ugh.”
Seo Juhan, who was about to get up, made a groaning sound and swayed, barely managing to support himself using the broad shoulder as a prop.
Ugh, my leg’s numb.
His leg hadn’t gotten blood flow because he’d been squatting. It felt like he had elephant legs. It was heavy as if soaked in water and swollen.
Though his leg still had no sensation, embarrassed, Seo Juhan hid his numb leg with a bright smile. He deliberately patted Go Un’s shoulder as if he’d done it on purpose.
“Ask again if there’s something else you don’t know.”
“…Yes.”
Go Un glanced up at Seo Juhan while slightly bowing his head.
Though it was a very slight nod that was too subtle to even call a greeting, Seo Juhan read gratitude from it. However, as if it was natural since he was a teacher, he patted his shoulder once more and started walking.
