After the fourth period came the long-awaited lunchtime.
Like Seori and Yuna, who were growling at each other, we got in line at the cafeteria with Ji-hye.
Everyone was deep into discussions about the performance assessments that happened in the morning.
Ji-hye clapped her hands.
“You guys were competing with numbers too! Our class hit a new record of 9.3!”
“Seriously, that was such a bummer, Ji-hye! I also got over 9 at the end!”
“So who came in first? Was it Na-me as usual?”
Ahem…!
“…?”
Yuna proudly lifted her chin and blew out a snort.
“You know Na-me helped you out entirely.”
Seori shot her a glare grumpily.
Since the end of the second period, Yuna’s heightened tension showed no signs of fading.
Having heard the details once already, Seori relayed the information to Ji-hye the same way.
“But injecting mana so accurately was super difficult!”
“Yeah, yeah, you’re amazing!”
“But how did Na-me figure out those numbers?”
The structure of the model magic circle was all beyond elementary school knowledge. It might even be middle or high school level.
It was understandable that Ji-hye was puzzled.
“The magic circle we received satisfied the harmonic mean. If the optimal solution from the north is 150 and from the south is 200, I figured the overall would be around 171.42.”
“What’s a harmonic mean?”
“Um… how do I explain that?”
If I said it was the reciprocal of the arithmetic mean of the reciprocals of the values, it wouldn’t make sense.
In situations like this, it was easier to explain with simple numbers.
“What’s the average of 1 and 1/3?”
“Um… hmm… I feel like I know this, we learned it but wait a second!”
Ji-hye squeezed her head trying to come up with the answer.
“3/3? No, that’s 1! 2/3?”
“Oh wow, our Ji-hye is smart!”
“Ahh, stop teasing me when you already know!”
She harshly swatted Seori’s hand away as it ruffled her hair.
“This is how you calculate the harmonic mean. Answer each of my questions. What’s the reciprocal of 1?”
“That’s 1.”
“Then what’s the reciprocal of 1/3?”
“Is it 3?”
“Now find the average of those two.”
“That’s easy. 2!”
“And what’s the reciprocal of that?”
“Um… 1/2?”
“Correct. That’s the harmonic mean. Got it?”
“No, I don’t understand anything!”
I thought I explained it pretty simply.
I guess I really have no talent for teaching kids.
If this simple math was confusing, how on earth will I start teaching Adella later? I have no idea.
Anyway.
After receiving our lunches in order, we went to the back corner of the dining area and each found our seats.
The seating arrangement was always the same: Seori would sit next to Ji-hye, and Yuna would sit next to me.
“Ooooh, bulgogi looks so delicious!”
Yuna grinned cheerfully while placing her tray down. Fortunately, she had piled her tray high with rice and meat side dishes today.
“Are you only going to eat that again today? Should I share a bit of my meat?”
“I’m fine.”
“If you eat so little like that, you might get sick later.”
That’s right, it’s because I can only eat a little when I’m sick.
Hoping that Professor Chun brings good news about potions soon, I popped a piece of bulgogi into my mouth.
Unlike my usual chatter, the atmosphere today was quiet.
It seemed like Seori and Yuna were rolling their eyes, thinking about the harmonic mean I explained earlier.
While Seori was struggling to understand, Yuna had grasped the concept to some extent and asked me again.
“I got the idea. But I still don’t understand what that coil magic is.”
“Are you curious about coil magic, Yuna?”
“Um… ah, yeah, I’m actually curious. Can you tell me…”
It was rare for Yuna to bow her head and ask like that.
Usually, she had a knack for refusing to admit when she didn’t know something, but this time, she really seemed interested in the magic.
How can I explain it easily?
There are limits to just talking about it.
“I’ll show you when I use a potion later.”
It seemed the best way was to demonstrate it directly.
*
Mathematics and theories are merely supplementary elements in explaining magic.
To truly understand magic, one needs intuitive observations on why such phenomena happen.
I took Yuna to the backyard of the school.
Right next to the wall separating the middle school division and the elementary division, I placed a potion bottle I took from class.
“Why are we here?”
“I came to show you magic.”
“It feels kind of scary since there’s no one around.”
Indeed, the backyard was overgrown with weeds, unlike the garden in front of the main building.
It certainly contributes to the eerie atmosphere.
However, I specifically chose this place because people rarely passed through.
“Did you bring the unused pen?”
“Yeah, this one’s broken so I don’t use it anymore.”
I removed the contents from the four-color pen Yuna handed me, leaving only the plastic shell.
With that, all preparations were complete.
“The model you saw earlier is a magic that generates heat with an electromagnetic coil. I’m going to try to cast it as closely as possible.”
Before opening the potion’s cap, I inscribed the shape of the magic circle on the ground.
It might look difficult to understand at first glance, but let’s channel my inner top instructor and simplify it as best as I can.
“This twisted wire is called a coil.”
“I know what a coil is! We learned it in science class in 1st grade.”
“Oh, that makes the explanation easier. This part here is the formula that allows current to flow through the coil.”
“Current?”
“I mean electricity.”
“Does it make electricity flow? Why?”
“When electricity flows through the coil, it generates heat.”
“So the coil gets hot?”
“Yeah, super hot.”
I skipped over the explanations about voltage, current, and resistance.
For now, it was enough to understand that current flowing through the coil makes it hot.
“What happens if the water gets hot?”
“Hmm… hot water?”
“Make it even hotter.”
“It turns into steam!”
“Exactly. From now on, we’re going to turn the liquid into gas using the coil’s heat.”
I first drew the engraved magic circle on the ground and connected it with the pen.
Since the part that operated with electromagnetism was complicated, I scrapped it and modified the magic circle to allow normal current supply.
[Engraving: Heat Transfer – Coil]
I also wrote additional details to ensure the pen would follow the principle inscribed in the magic circle.
“Yuna, think of the inside of the pen as having a tiny coil.”
“Uh-huh.”
“If we drop the potion on a hot coil, what do you think will happen?”
“The potion will turn into smoke, right? Or… will the coil cool down?”
“To prevent the coil from cooling down, I put some cotton in the middle. We’ll drip the potion onto that cotton one drop at a time.”
“Then it will turn into smoke!”
Yuna answered confidently, and I confirmed her response.
As soon as I opened the potion, I slipped the pen into the flask’s opening.
I filled the remaining space with clay I had left over from art class last week to prevent the residue from oxidizing.
It formed a ridiculous-looking structure, but it was the easiest way to explain this magic.
“In the end, the key to this magic is resistance. Look carefully. If I inject mana into this, the total resistance will be 0.5 ohms, you know?”
Tap tap-
I tapped the pen twice to activate the engraved magic circle.
As soon as the magic circle on the ground lit up, I placed my mouth over the end of the pen and inhaled.
The potion was absorbed by the cotton and vaporized immediately due to the heated coil, producing steam.
The gas flowed from the pen to my mouth, then to my throat and lungs, and as I exhaled, a thick mist spilled out, swirling around.
“Whooosh.”
Just as I expected. Taking the potion like this definitely made it less bitter.
Moreover, the nebulous mana, once inside, tends to stay in the body efficiently, making it no different from taking it in liquid form.
Why didn’t I think of this method until now?
It was a moment that made me realize how desperately creativity is needed in life.
“Wow! How did you do that, Na-me? Smoke came out of your mouth!”
“Shall we double the resistance this time? That way, will double the smoke come out?”
“Even more than this?”
Yuna seemed excited, which in turn lifted my mood.
I changed the resistance to 1 ohm and took another puff from the pen.
“Whooosh.”
“Wow! There’s so much smoke! Cough cough… It’s awful.”
Yuna waved her hand at the now doubled smoke, only to end up coughing as some of it sneaked into her nose.
“You shouldn’t try to inhale it on purpose. Do you want to try it? It won’t do anything!”
“I almost choked last time and nearly died…”
Yuna vigorously shook her head.
If she doesn’t want to, there’s nothing I can do.
Before the fifth period started, I focused on blowing out the remaining potions to use them up quickly.
While Yuna observed how the magic circle worked, she muttered.
“But it looks just like cigarette smoke.”
“Yuna, you’re really smart, you know?”
“Huh?”
“This works on the same principle as cigarettes.”
“What?”
As I exhaled the last puff, I finished my potion intake for lunch today.
The engraved magic circle could last a long time, but it seemed twenty times was the limit; I couldn’t expect any more heat.
“This is what we call an atomizer. It’s a device found in e-cigarettes.”
Do kids these days not know about e-cigarettes?
