When Hermione Granger received her letter, she thought it was a joke.
There was no such thing as witchcraft, first, *obviously,* and even if there were, why would it be taught separately from "wizardry", which of course was not a thing either, let alone something you went to school for.
Still, this elaborate and bizarre of a practical joke deserved some kind of a response. So Hermione borrowed some of her father's stationery, and her mother's second-best fountain pen, and composed a letter of her own.
Dear Deputy Headmistress McGonagall, (the letter began)
I was surprised and delighted to be accepted into what I can only assume is the most prestigious school that no one has ever heard of in all of Britain. The course load sounds rigourous, challenging, and not at all made up.
It is with deepest regret, therefore, that I must admit my local bookshops are absolutely bereft of the fine work of Messrs. Goshawk, Bagshot, Waffling, Jigger, and Spore. Having no wish to arrive at school without a full set of textbooks, I must request assistance in procuring the required course materials.
Yours sincerely,
Hermione Granger
Head of Class
Glandrix Academy for Exceptionally Reasonable Youth
PS. What exactly does a Supreme Mugwump do? Is Mr. Dumbledore sure he wants to hold important, and no doubt exhausting, positions for the Order of Merlin, International Confederation of Wizards, and Hogwarts School simultaneously? What size of telescope is appropriate for a first-year? Will leather work gloves suffice, if they are very thick? I have a high-precision scale made out of stainless steel; will that suffice, or does it have to be brass?
Hermione folded the letter carefully, slipped it into a plain white envelope, and addressed it to Minerva McGonagall, Hogwarts School of Witchcraft and Wizardry, Somewhere in Britain, Apparently. She affixed the usual amount of postage, and left it in the mail slot. She then went on about her day, and the whole thing fell out of her mind completely.
The next day, Hermione was buttering her toast when she heard a thump, a squawk, a ruffling of feathers, and several frustrated klumping sorts of sounds.
"Check what it is, love?" Hermione's father said, looking at her. Hermione rolled her eyes, and went to look.
There was no particular reason why Hermione's parents made her do things like set the table, or clean her room, or investigate a mysterious noise that still, after all this time spent thinking about how silly and pointless and annoying adults were, would not stop its rapid, rhythmic thumping.
It was the mail slot, Hermione learned, turning a corner through the living room to the front entryway. It was jammed with what looked like thirteen mail slots' worth of full-color advertisements. And - it must have been Hermione's imagination, but she could have sworn that some of the pictures had been moving.
There was a sound like a determined alien bird-mother defending her nest from would-be predators, and with a final, mighty thunk the entire collection of pamphlets, brochures, magazines, flyers, album covers, posters - some with Hermione's face awkwardly superimposed into graduation robes - bath toys, pens, T-shirts, scrolls, bubbleheads of what had to be a mascot, and tiny pouches of jelly beans, cascaded into the room and covered the floor.
It was only much later, after finally sorting and glancing through all the promotional materials, with all their sales copy and instructional advice, that Hermione finally accepted the truth.
There was no doubt about it. Hogwarts was a real place. It had to be. They hadn't answered a single one of her questions.