The Medicine Bottle

I'm pulling out yet another fried graphics card from an old desktop machine. The card is so plastered with dust I'm considering actually writing my name in it when she comes into my room. She's thirteen. She slings down her school bag down in the corner and then slumps against the wall. She's wearing black-rimmed cateye glasses.
"For feck's sake..." I comment, blowing hard on the PCI express slot and generating a dust cloud. "...they should make mini hoovers for this kind of job."
"They do dad," Charlotte says flatly. "You just don't have one."
"Hmm, okay. What's with the specks?"
"What do you mean ‘specks'?"
"Glasses. Those things on your nose."
She shrugs. "I found them in the loft."
"Hmm, so you just found them up there? So how come you're wearing them?"
"Because I like them? Is that a crime?"
She's talking to me at the moment like everything's a question I should really know the answer to. I glance at her and can't help but smile.
She walks over to the computer I'm working on and touches the top of it. "Dad?"
"You know that funny little bottle I took to school for my art exam?"
"It shrank."
"Did it?" I clip an overpriced and overclocked graphics card into place and give the whole shebang another huge dust-removing blow. Sitting back in my chair and rubbing my dirty hands, I let what Charlotte just said seep.
"What do you mean ‘shrank'?"
Charlotte rolls her eyes. "I mean it shrank, like, got smaller?"
Oh yeah, stupid me, I think. She shuffles over to her bag, unzips it and takes out her pencil case. "It shrank by like, a whole centimeter."
"A centimeter?" I sit forward. "Holy cow."
"Dad, stop taking the piss."
"I'm not."
She puts the medicine bottle down on the desk in front of the dismantled PC and slides the glasses down her nose, as if to examine it.
The bottle looks pretty much exactly like it did this morning.
Charlotte pushes the glasses back up her face.
Just for a moment, with those glasses on, she reminds me of
.........................I pick the bottle up and turn it around in my hands. It feels smooth and light and a bit weird...
"It looks… pretty similar." I say carefully.
"I measured it," Charlotte says. "Like, before I started the still life? And then after lunch break."
"Are you sure you measured it right the first time?"
"Well, yeah," She does the eye-roll thing again. "It was ten centimetres, exactly. Now it's nine. Do you have a ruler? Check it with a ruler."
I do as I'm told, and then place the bottle back down, gingerly, like it might bite. "Well. That's bizarre. I've never come across a bottle that shrank. What do you think we should do about it?"
Charlotte folds her arms and moves back against the wall again. She shrugs. "Isn't it obvious?"
I stare at her, waiting.
"We put it on eBay," she says.