Teaching Little Sister to Say "Big Sis"
After that day, Mom restarted her subscriptions to overseas math journals, which she'd canceled when she graduated with her master's.
Well, exactly speaking, I begged her to do it.
Inventiones Mathematicae, Annals of Mathematics, Journal of the American Mathematical Society.
On the days new issues arrived, I'd wake up early in the morning and wait by the front door for the delivery guy.
"Package uncle! Thank youuu-!"
"Oh my, what a polite little lady. You're welcome."
I'd snatch the envelope and dash—thud thud thud—over to the sofa, ripping it open.
Ahh, look at that glossy sheen.
Papers on complex analysis, combinatorics, algebra, topology—all these diverse fields bundled together in one glorious stack.
To me, this was better than any dress-up doll!
"Mom! Mom! This month's new issue came!"
When I bounced in place with eyes sparkling in anticipation, Mom would sit on the sofa with a helpless smile, and I'd burrow right into her lap.
This became our routine.
While reading the papers aloud, if Mom skimmed over a part she didn't understand, I'd pretend not to get it, tilting my head and asking questions.
"Mom, why's this condition needed here?"
"Hmm… hold on a sec."
While she pondered, I'd swing my feet back and forth.
That's right, almost there.
"…Ah! Without this condition, the convergence later on wouldn't hold."
"Ooo-!"
I'd clap wildly. Mom would glance at my face, then chuckle softly.
"Why are you more excited than me, A-yeon?"
"Heehee. 'Cause Mommy explained it so well, I'm happy!"
Of course, she didn't think I actually understood these papers.
Instead, since the logical progressions were all in English, I'd practice my listening with her pronunciation, while she brushed up on math she'd set aside for a bit. That's how our time flowed.
It's like how parents read English picture books to kids these days, right? Pretty similar.
But whenever I asked about something I was curious about, she'd think it over sincerely and answer.
That was more than enough.
About four months passed.
In that time, books from the high shelves in the study were gradually migrating down to where I could reach them.
Dad brought home newspapers and journals too, piling up.
Math, physics, chemistry, biology, economics, engineering. Fields varied wildly, but I absorbed them all without discrimination.
The more knowledge I crammed in, the warmer my head felt—like synapses exploding in growth, linking up, linking up, linking up again.
I could really feel how synapse density peaks at this age, the tightest connections of a lifetime.
Perfect. Won't waste a single second of this golden time.
So I added one more routine: multilingual skills.
With my brain growing explosively right now, this was the prime window for language learning.
Languages stick deepest when learned at this stage.
Chinese, Japanese, French, German, Spanish. Let's start light with these?
Luckily, in my past life hopping between international conferences, I'd studied them to basic conversational level.
Skeleton's there—just need to add the meat this time.
I tugged at Dad's pant leg.
"Daddy. Daddy."
"Yeah? What's up, sweetie?"
"Can you buy this for me?"
I held out a memo with my careful scribbles.
[Chinese Conversation, Japanese Conversation, French Conversation, German Conversation, Spanish Conversation]
Full conversation books, even with MP3 files for speaking and listening practice. My top picks.
Dad took the memo, read it once, twice.
"…Our little girl?"
"Yeah?"
"You need all these? For real?"
"Yup!"
I nodded vigorously.
Dad glanced at Mom. She gave a slight nod.
"…Got it. I'll get 'em. But hey, A-yeon, aren't you getting smart too fast? Daddy's starting to get jealous."
"Heehee, then study with me, Daddy!"
"Hmm… Should I? English together?"
"Sure!"
Okay. Viral study marketing success with both parents.
Teaching Mom math, Dad English. That's how filial I am.
Yoo A-rin, 11 months old.
I was reading my conversation books in the living room when I caught a vibe and looked up.
Munch munch. A-rin was working her lips.
"Gasp…!"
Having been through it myself just two years ago, my gut screamed: first words event!
A baby's inaugural utterance.
From a language acquisition view, it signaled the Broca and Wernicke areas linking up—input and output forming circuits.
But my very first thought in this pivotal moment?
I want her to call me 'big sis' first…!
I wanted A-rin's first word to be 'unnie'—big sister.
Before Mom, before Dad. I, Yoo A-yeon, wanted to be the first she called.
Such a simple, clumsy desire. The kind a little kid would have.
But hey, I am a little kid, so it's fine, right?
I closed the book and crawled over to A-rin.
Sat right in front of her, locking eyes. She beamed at me.
"A-rin, copy me. Un—nie."
"Ah-woo."
"No, watch close. Un—nie."
"Woo-woo."
Yeah, not that easy.
'N' is a tongue-tip sound. Gotta press the tip precisely against the roof behind the upper teeth.
Pulling the tongue muscles up—a real advanced move for babies.
Meanwhile, 'M' and 'B' are lip sounds. Just smack and release the lips—way easier than 'N'.
Plus, they use the same muscles as nursing instincts, so babies master lip sounds first.
Statistically, A-rin's easiest first word would overwhelmingly be 'mama' or 'dada'.
A lopsided battle from the start, win rate abysmal.
But.
Doesn't mean I'm giving up.
Because I'm her big sister…!
I grabbed her squishy cheeks with both hands. "Wha?"
Locked eyes tight.
"A-rin, big sis big sis big sis big sis…"
Then I hammered 'unnie' into her infinitely.
Dad peeked from the sofa.
"Whatcha doing, kiddo?"
"Sorting out the hierarchy for A-rin—who's big sis."
"Pfft, what's that? Teaching her 'unnie'?"
Dad snuck over and squatted down.
"But 'N' sound's still tough for her. Usually comes around one year. Still a month away."
"Yeah… but…"
Dad glanced at Mom. She chuckled and shook her head.
"A-yeon, Daddy's right. Better to wait naturally than force it—"
"Hng… she won't say it…"
I pouted a bit, lips out.
"I wanna hear 'big sis' from A-rin first…"
I mumbled around my finger. Parents exchanged knowing looks and giggles.
"Alright then. We'll cheer you and A-rin on. Fighting!"
I kept intense eye contact, running one-on-one tutoring.
"Unnie. Unnie. Watch. Tongue goes up to the roof like this. Like—ahh—"
I opened wide, exaggerating the tongue tip touching the roof.
Whether she got my efforts or not.
"Hee hee hee."
A-rin just cracked up at my open mouth.
Next day. Day after. Day after that.
I skipped books whenever I could, plopping in front of A-rin.
"Unnie. Unnie. Unnie."
She stared at my mouth, lips twitching.
"Uh… uhh—."
'M' incoming.
The natural lip-smack trajectory.
No. Not 'm'.
Ahh—I went slower, mouth wider, showing the tongue rising.
"Un—nie." Her eyes followed my mouth.
"Uh… uhh…"
"Yeah, tongue up."
And then, from A-rin's mouth.
"'N'…"
"…!"
I froze, breath caught.
"'N'… neu…"
"Yes! That's it! Good job!"
I clapped excitedly, and A-rin, sensing it was right, kept practicing the 'N' sound with her tongue.
I ran private drills for over 30 minutes.
And finally.
"Ni… unnie—."
That longed-for word from my little sister's lips—I was so thrilled I felt like I could fly.
"You did it! A-rin's the best!"
I hugged her tight. She grinned.
"Hee hee hee, unnie—!"
"Yeah! Big sis! A-rin's big sis!"
"Honey, look at that."
"Yeah… I see."
Han Seol-ae and Yoo Jin-hu peeked from behind the wall, watching the sisters secretly.
Bonus: filming on their phones.
"She skipped her favorite books for days to train with A-rin, and boom—success."
"Seriously, that determination. Our girl's something else."
They'd rooted for Yoo A-yeon, but honestly never dreamed 'N' would beat out 'M' or 'B'.
Sisters two years apart often clash—invading territories, vying for parents' attention as they grow.
But Yoo A-yeon sacrificed her beloved books to spend time with Yoo A-rin.
Impossible without love.
Han Seol-ae and Yoo Jin-hu figured those two would always get along great.
That night, I lay in bed staring at the ceiling, too pumped to sleep.
Roll roll.
'Unnie.'
A-rin's first word. Not Mom, not Dad—big sis.
…Did it feel this good?
I'd called myself her big sis plenty, but hearing it from her lips? The resonance hit different.
"Hee hee hee hoo hoo."
Whoosh—I yanked the blanket over my head and giggled to myself, safe from prying eyes.