It's true I've been haunted by the voice of Baekhyun's dead twin brother. Why me? Her heart pounded, fear making a cold sweat break out on her forehead. She mopped it away with her forearm. "Park Jiyeon, you're a brave woman. Don't fear ghosts; they cannot harm you, and one day you will be a ghost too. Ghosts can be your friends—receiving is the frontier of the future," Jiyeon told herself, trying to neutralize her fear. "Remember that you are with God. God will protect you. God is stronger than Satan and all the Devils on earth." She exhaled slowly through , trying to relax her pounding heart. Then she edged her way towards the entrance door, her mind still racing.

What Blondie—or more precisely, Baekwoon told her about Yoona having an intense fear of geckos was right—did it mean all what he told her in her dream was true? They had a lot of things in common and shared the same habit of eating only egg whites and leaving egg yolks like eyes? Having a lot of things in common was the reason for his obsession with her? And what was the incident? Jiyeon came to a halt outside the entrance door. Trying to control her racing mind, she took a long breath, pulling it deep into her lungs. Stop. She held it for a few seconds. The release helped to calm her. Better. Much better!

Then Jiyeon walked along the corridor to her classroom. Classes had begun. Students were on task. She stopped in her tracks and watched Yoona from outside, looking in through the glass window with an unwavering fixation. Yoona was writing down the chemical formula of methane on the blackboard and also drawing the schematic drawing, showing how the atoms of hydrogen and carbon were linked in a molecule of methane.

"Ms. Im, I'm sorry I will threaten you again because I have not been satisfied yet. I have a few things I want to ask you," Jiyeon mumbled inwardly. "I'm really sorry for a tear that I made you shed."

Shaking her head, she continued on her way. Her steps were hurried. "Park Jiyeon, stop thinking about Baekwoon and focus your mind on teaching, okay?" she told herself and nodded at her own words. Her students were engaged in chatting, throwing paper darts as she entered the classroom. "Good morning class," Jiyeon greeted as she walked over to the teacher's desk. No response. "Good morning class!" she shouted, dumping her bag on the desk with a resounding thump.

The pupils stood up nervously. "Good morrrrning, Teacher Park," they greeted her in unison, except Taeyong, who was busy folding a sheet of paper into a plane. Jiyeon instructed them to sit down. Their chairs scratched the floor as they sat down.

"Jiboast, why are you mad? You know you came late again!" Taeyong tossed the paper plane. It soared into the air and landed right on the teacher's desk.

, he really calls me Jiboast! Jiyeon picked up the paper plane and crumpled it, gritting her teeth as she looked at him. Taeyong's face appeared neutral in emotion, but his gaze was sharp.    

"Lee Tae—" Jiyeon's scream was cut off by the smooth, melodious voice whispering in her right ear:

"My girl, no one knows the meaning of Jiboast, except you and him. He does this sort of thing because he's looking for a negative reaction. He expects you to blow up, which is evidently amusing to watch. Don't be his entertainment. Look at other students; they seem to get scared."   

Jiyeon gazed at all the rest of the students. Everyone was sitting in stony silence with their arms folded on the tables and their heads down. Did I scare them? A silent sigh slipped through her lips.

The voice rang in her left ear, dressing its words in a joking tone, "My girl, your scream is scarier than the sound of a balloon popping."

"That's not funny," Jiyeon muttered under her breath, tossing the crumpled paper into the trash can beside her desk. She then cleared in an attempt to gain the students' attention. They raised their heads to gaze at her. She smiled at them. "Okay, class. Instead of checking your homework, I'll give you quizzes similar to the homework assignment," Jiyeon announced in a resolute but soft voice. A few students groaned just a bit.

She walked over to the blackboard and began writing down a set of quizzes. Having finished writing on the board, Jiyeon turned around to face her students. "Whoever gets the highest score will get a prize from me," she told them, a smile hovering on her lips. She hoped that the prize could motivate students to participate in the classroom.

Only two students seemed excited; bright smiles dawned on their faces, while the rest of the students looked at each other in disbelief.

"Great, this will be fun!" Eunkyo exclaimed—simultaneously the male student with a shaved head, wearing round glasses, said, enthusiasm lacing his voice: "What's the prize?" 

They stared at each other; then Eunkyo rolled her eyes at him. The shaved head boy stuck out his tongue at her in return before looking back at Jiyeon.

She smiled at their enthusiasm. "The prize is a lunch treat. You can eat whatever you…" Jiyeon trailed off as she saw Taeyong rise from the chair.

Taeyong stood by the window, looking out. "What are you doing!" he called out. All students turned. Their gazes settled on him. From where Jiyeon was she couldn't see who he was taking to.

He called out again, "What are you doing!"

It seemed as if he was addressing somebody high up somewhere. Jiyeon couldn't help being curious, and her ears strained to hear the answer, but there wasn't any. In spite of that, Taeyong kept on calling out, "What are you doing?"

Irritation bubbled inside her. Letting out an exasperated sigh, Jiyeon went over to the window to see who he was talking to. When she stuck her head out of the window and looked up, she saw it was a pair of swallows making a nest under the classroom eaves. He was talking to the swallows!

"How old are you, Lee Taeyong?" Jiyeon muttered through gritted teeth. "Asking the swallows what they are doing is stupid. They can't speak, Taetrant."

The rest of the class brought their gazes back to the blackboard when Jiyeon walked over to Taeyong. The shaved head boy stuck his fingers in his ears as if anticipating any loud noises.

"He's looking for a negative reaction, my girl," the soft melodious voice whispered in her right ear. "Don't react in a way he expects you to."

Jiyeon tapped his back, and Taeyong turned his head to look at her. "What's up?"

She pointed to his chair. "Sit back down," Jiyeon said very slowly, then pointed to the door, raising the pitch a bit, "or get out of my class. Don't disturb my lecture." She shot him the most deadly glare she could muster. 

His mouth flattened into a straight, tight line, and his eyes narrowed. He sat back down. Jiyeon bent over and whispered in his ear, "I haven't forgotten about what happened to my bike. I shall give you two days. If in forty-eight hours you cannot find the real culprit, I'll call your parents. Understood?"

Taeyong squeezed his right hand into a fist. "Yes, Jiboast," he hissed.

Jiyeon straightened up and patted his head, saying, "Good, Taetrant." A cynical smile tugged at the corner of . Then she went back to the teacher's desk and leaned against it with crossed arms, facing the students. "Alright, class. I will read each question," Jiyeon began, "as soon as I finish reading, raise your hand if you know the answer, come to the front of the class to solve the problem on the board. Do you understand?"

"Yes, I understand," Eunkyo and the shaved head boy said in unison, while several students nodded, and the rest of students remained silent.

Jiyeon looked at the blackboard and cleared before she recited the first question, staring at the whole class: "Set up an integral that computes the arc length of the segment of y equals sine x between x equals zero and x equals pi."

Four students immediately sprang to their feet—and their shoes thudded against the floor as they made their way to the board, which surprised her. Eunkyo was the first person who picked up a piece of chalk from the ledge, so Jiyeon told three other students to go back to their places and focused her attention on Eunkyo.

"Since y-dash equals cosine x, I get—" Eunkyo scribbled out the integral:  . Then she turned to look at Jiyeon, as though asking for confirmation if she had answered correctly or not.

Clapping her hands together, Jiyeon smiled at her. "Good, that's correct. Using the Composite Simpson's Rule, the value of the integral is seen to be approximately three point eight two zero two."

"Yes! Yes! Yes!" Eunkyo chanted and danced, whirling slowly to the left and right. A couple of her classmates erupted into rhythmic clapping.

Taeyong let out a short whistle. "Kyokyo, shake your hips!"

Eunkyo rolled her eyes and headed back to her seat. Jiyeon shook her head at her reaction. She then opened her bag and took out the grade book and a pencil. She opened the book and made a tiny circular mark next to Eunkyo's name to indicate that the student had participated and answered correctly.

The students lapsed into dead silence when Jiyeon moved to the center of the front room. She stood with her arms folded across her chest and legs apart, staring at them without blinking. They ducked their heads down, except Taeyong, who kept his gaze fixed out the window.

"My girl, your body language displays aggressive and domineering. It scares your students," the soft, caring voice whispered in her right ear.

"I feel so comfortable and so confident standing like this," she muttered under her breath, and then she clapped her hands, trying to diffuse the tension in the room. Students' heads slowly lifted, their eyes reluctantly glancing forward. She flashed a huge smile. "Okay, class, let's continue," Jiyeon said in a soft voice and looked over her shoulder at the blackboard, then back at her students. She recited the second question, "What is the volume of the solid obtained—"

"You've written those questions on the board. Why do you need to recite it?" Taeyong got to his feet. "That's just a waste of time, Jiboast!"

Don't call me Jiboast in front of other students, Lee Taetrant! From deep within her chest, she felt the hot anger rise. "Sit back down!" Jiyeon instructed in a loud voice, booming in the still air as the entire class fell silent.

"Didn't you tell us to come to the board to solve the problem?" Taeyong took a casual stroll to the front of the class. "I know the answer, youngest teacher." He picked up a piece of chalk from the ledge.     

Her eyes darted over to the window as Jiyeon took a few deep breaths, inwardly calming herself. Feeling relaxed, she returned to the teacher's desk and sat down. She watched his hand fly across the board as he scribbled out the solution to the problem.

"Are you sure you can solve that problem?" Jiyeon questioned as he erased the expression (x² – x/2). Yesterday, he got kicked out of class for disturbing the class and disrespecting her when she explained this topic to the class. So it seemed almost impossible for him to solve the problem.

"I'm sure I can! I asked Chaeyeon to tutor me about this topic last night." His voice oozed confidence as the words rolled from his lips. The chalk scraped loudly against the board as he rescribbled the expression. Then he stood there like a statue with the chalk in mid-formula.   

Letting out a sigh, Jiyeon got to her feet and moved to stand beside him. She spoke in a low voice, pointing to the expression (2x – x²), "This is wrong. This should be left-parenthesis x over two—"

"I know—" Taeyong rolled his eyes, then rubbed his nose, turning it white with chalk dust. He erased it and shouted in a loud, clear voice as he rewrote the expression, "left-parenthesis x over two minus x squared right-parenthesis!"

Jiyeon looked at him, flattened into a thin line of irritation. Once Taeyong finished calculating, he jumped up and turned to face his classmates.

"Hey guys! Look, I've managed to find the volume," he said, sounding prideful as he pointed at the blackboard behind him. "The volume of the solid is pi over ninety-six!" He clapped his hands, then broke into a dance, wiggling his hips. All-female students were squealing, except Eunkyo, was busy scribbling in her notebook, whilst all the boys were whistling and cheering, except the shaved head boy, who was cupping his hands over his ears when Taeyong his pelvis.

Jiyeon rolled her eyes in disgust while gritting her teeth. She felt like she was in a ty concert. She tapped the blackboard with a wooden ruler and regained everyone's attention. "Taeyong, you can go back to your seat now," Jiyeon said, trying to sound calm.

The right corner of his mouth twitched as he stared at her. "Go back to your seat," Jiyeon repeated, shooting him a stern glare. Without saying a word, Taeyong made his way to his seat, his hips swaying in a taunting way as he walked.

Releasing a loud sigh, Jiyeon went back to her desk. She sat down and opened the grade book. "Great job tutoring him, Chaeyeon." She made a tiny circular mark next to Taeyong's name with the pencil.

Jiyeon continued her lecture with problem solving quizzes. She didn't change the rule, although Taeyong had complained it. She could sense that there was competition between Eunkyo and the shaved head boy. They were the first people to raise their hands as soon as she finished reciting a question. However, Jiyeon chose another student to come to the board to solve the problem, so all students could participate in this game. When the student answered incorrectly, she made a tiny 'x' mark next to the student's name to indicate that the student had participated but answered incorrectly and explained how to solve the question on the blackboard.

She cleared and began to read the last question: "Find the volume of the solid obtained by rotating the area between the x-axis and the graph of y minus one over x cubed from x minus one to x minus b—"

"I know the answer." The shaved head boy sprang to his feet and darted to the blackboard.

His enthusiasm brought a smile to her lips. Jiyeon watched him scribble down step after step as he went through the whole process in detail. It won't be that messy if you use the washer method instead of the shell method. She shook her head. When he finished, he turned to face her.

Smiling, Jiyeon rose from her chair and approached him. "A good attempt."  She tapped his shoulder lightly. "Go back to your seat. I'll explain the correct answer."

The shaved head boy nodded and walked back to his seat with short steps, his head held down. He seemed disappointed.

"My girl, you're a good teacher. I admire you very much," the voice rang in her right ear, soft and sweet.

Jiyeon shook her head very slightly and erased everything that was on the board, then drew the graph with white, green and red pieces of chalk. She knocked her fist against the blackboard and her sharp gaze carefully scanned students, saying, "I'm going to explain how to solve the last question. Pay attention, okay?"

The students nodded, sat straight up, folded their hands on top of their tables, and looked straight ahead.

Jiyeon smiled. "Here the green line is x minus one and the red line is x minus b," she began, pointing at the vertical lines on the graph, "we're revolving around the x-axis, so washers would be vertical and cylindrical shells would have horizontal sides. Figuring out the height of a shell is clearly going to be messy, so let's use washers." She looked at her students. "Since the washers are vertical, their area changes as x changes, so we should express the area of the washer as a function of x. You understand?"

The students nodded again. She took a deep breath before continuing, "The washer is actually a disk with radius 1/x³ – 0 – 1/x³, so we see that the cross-sectional area is—" Jiyeon scribbled the equation on the blackboard: A (x) = π (1/x³)² → π . 1/x⁶. "Since the region runs from x minus one to x minus b, these are our limits of integration, so let's integrate to find the volume"—she scribbled the formula—"the volume of the solid is pi left-parenthesis one over five minus one over five b to the power five right-parenthesis." She placed the chalk on the ledge and turned from the blackboard. "Does anyone have any questions?"   

No response. Students were busy copying what she had written and drawn. Jiyeon walked over to her desk, clapping her hands together to shake the last remnants of chalk dust from her hands. Sighing, she plopped down in the chair, reached in her bag and pulled out the exam papers.  

"Class, I've graded your tests, and the average grade is a C," Jiyeon announced. "The good news is only one person got a perfect score; the bad news is one person earned the lowest score, F."

The resonant tones reverberated through the room as some students said simultaneously:

"Who got the lowest score?"                         "Who got the perfect score?"

"The person who earned the lowest score is the person who got caught cheating on the test." Jiyeon darted a quick look at Taeyong, then looked at Eunkyo, her lips slowly curving into a smile. Eunkyo had her hands clasped together in a prayer-like gesture, her eyes closed as if in anticipation.

"Congratulations, Seo Eunkyo. You got the perfect score," Jiyeon said.

Eunkyo's eyes jerked open, a look of disbelief crossing her face, then she smiled as her classmates congratulated her. As Jiyeon was returning the exam papers, calling each student's name, the bell rang to signal the end of the first period and the start of the next period. When Jiyeon finished, she immediately gathered her things in a hurry, stuffing everything in her bag, then left the classroom and headed straight to another class.

"Ms. Im, wait!" Jiyeon called out when she saw her walk towards the stairs with the book in her right hand. Yoona quickened her pace, ignoring her.

"Stop or gecko!" Jiyeon accelerated her stride.

Yoona came to a stop at the bottom step of the stairs and turned around. She pulled the book to her chest, crossed it with both arms, cradling it. She narrowed her glare at Jiyeon, her lips pressed into a tight line. "What do you want?" she asked crossly as Jiyeon climbed up onto the bottom step.

She brought close to her ear. "Let's meet up at the school rooftop at recess. I have a few things I want to ask you," Jiyeon whispered, "if you refuse, I swear to God, I'll hunt you down and give you the real gecko."  

"Miss Park Ji-Yeon, I'm older than you," Yoona hissed, "so you've got to respect me. It seems like your parents didn't teach you to respect—"

"My parents did teach me moral values. Don't drag them into this. They will surely punish me if they know my threatening behavior," Jiyeon interjected through clenched teeth. She wanted to punch her. The urge was so powerful—she had to curl her hands into fists, fighting for some self control. She took a slow, deep breath, then exhaled very, very slowly, releasing her anger. "I'll wait for you there." She walked off towards her class.

As Jiyeon entered the classroom, her students stood up and greeted her in unison, "Good morning, Teacher Park."

She made them sit down by means of a gesture of the hand and without greeting them. Yoona's words killed her mood. Jiyeon had always wanted to punch people who had a tendency to blame the parents for their children's actions. Most parents wanted their children to grow up to be good, kind people. That was why they taught their children moral values in the home and sent them to school.

We are responsible for our actions: attitude, behavior, thoughts and words. No one else! Jiyeon sat down and placed her bag on the desk. She was aware of her own action anyway. "Park Jiyeon, let's focus your mind on teaching again," she silently told herself, and she nodded at her own words.

Her gaze shifted to take in the whole class at once, and a warm feeling blanketed her heart at the sight. Students sat neatly and politely, organized perfectly in rows. An immaculate silence spread throughout the classroom like a divine fog. They looked so serene as they waited attentively for her words. Jiyeon opened her bag and took out the exam papers she had graded. She called out the name on each paper, and each student came to her desk to claim it. Once she had done, she explained how to solve difficult questions that most students had answered incorrectly in the exam with methods they could understand easily on the blackboard. The explanation took fifteen minutes, and she continued her lecture with problem solving quizzes like she did in the previous class until the bell rang to signal recess time. The soft chatter and laughter of students could be heard.

"I never thought would happen: me actually enjoying learning Math!" one of her students boomed out, her loud, strong voice echoing through the classroom.

Her student's loud voice annoyed her, but her words brought a smile to her lips. "See you next time, class," Jiyeon said before walking out of the classroom. She headed off to the staff room. Some students greeted her with smiles as they passed by, and she returned their greeting with a tiny nod.

The staff room was noisy with the teachers joking around and talking loudly when she entered. She greeted other teachers with a smile as she went to her desk and plopped down in the chair. Remembering that her father would call her, she reached into her bag and pulled out her mother's cell phone to check it to see if she had missed any calls. There was none. Her father hadn't called her yet. She slipped the phone into her pants pocket, her eyes fixed on Yoona, who was standing near the windows while chatting with male teachers. It seemed like that new teacher already got along well with her colleagues.

Jiyeon shook her head, clicking her tongue against the roof of when Yoona laughed and lightly smacked P.E. teacher's upper arm with the back of her hand. P.E. teacher was the only male teacher who hadn't married yet. He was about five feet, eleven inches tall, dressed in blue tracksuit bottoms and a flattering white t-shirt, showing off his upper body muscles. He had short, wavy brown hair and tan skin. He was a year younger than Yoona—his name was Choi Minho.

"He is her new target. She's going to break his heart," the voice rang in her left ear, sounding angry. "She's a player. My girl, tell him to stay away from her."

"Why are you angry?" Jiyeon mumbled under her breath, putting her bag into the drawer. Then she rose from her chair and walked out of the staff room while imitating the sound of a gecko out loud, as if signaling Yoona to follow her, "Tik, tik, tik. Tik, tik, tik."

Stealing a glance behind her, she saw Yoona follow suit, walking with short steps. Jiyeon's face split into a huge smile. She kept her stride steady as she walked down the hallway towards the stairs. When her heels bumped into the bottom step, Jiyeon halted, waiting for Yoona.

"Ms. Im, do you like Mr. Choi?" Jiyeon asked as they climbed up the stairs towards the rooftop.

"None of your business!" Yoona darted a quick sideways glance at her. Jiyeon curled her upper lip to one side at her brusque response. Once they had reached there, Yoona immediately sat down on the floor, her legs stretched out, and her back leaned against the fence. "What do you want to ask me?"

Jiyeon sat down beside her and crossed her legs. "Hear me out and answer me honestly and truthfully, okay?"

"You sound like a boss," Yoona responded, closing her eyes. "Go ahead, youngest teacher. Just don't ask me about my personal life."