So, let’s say you’re a Muggle and suddenly you are a Muggleborn and then you have to pack all of your things into a bag and whisk off to Diagon Alley to buy supplies for an unexpected journey that you aren’t quite sure about. An explanation would be helpful, yes? Welp, too bad, you’re a wizard now and you have to figure things out on your own.

In JK Rowling’s universe, Harry Potter frequently acts as a substitute for the reader. Most of us aren’t magical and we know nothing about magical worlds so as Harry learns, we learn. This is a classic narrative device and it can work well to convey information to the reader about the fantasy setting. But the way in which the information is conveyed can be just as enlightening as the information itself. Harry Potter is frequently tossed into chaotic situations that he is ill-equipped to navigate because, despite being born of a wizard and witch, he was raised as a Muggle. He knows nothing about floo powder, brooms, potions, or wands and most of the time other wizards and witches either patronize him or scorn him for his (understandable) ignorance. It is very rare that anyone takes Harry aside to give him a calm explanation of what he is expected to do. Dumbledore is particularly bad at this, although his motives are for pretty sinister reasons. (Best way to hide a Horcrux? Keep it in the dark!)

At any rate, someone needs to write the equivalent of Fast Facts for Free Agents for Muggleborns and Muggle-raised kids who come to Hogwarts and need a crash course in magic. (And if you want to more about that, go read the excellent Akata Witch by Nnedi Okorafor!)
Also, who teaches magical kids how to add? How are they learning to read before they get to Hogwarts? Are they home schooled?

Also, we’re back, like an old, bad penny. A great deal of red wine and a moderate amount of dandan noodles went into this page, so please enjoy! -Vox

↓ Transcript
AMA: But we will use a bit of magic to get ourselves to London in a blink, can’t waste time with muggle travel.
SETH: Uhhh, is it going to work? I don’t know how to do...anything.
AMA: Of course you don’t, young pup! You haven’t even a wand yet, do ya? No, we’ll be taking a portkey. Too far to apparate, wouldn’t want you getting splinched on your first time.
SETH: What’s spl-you know what? I don’t think I want to know.
AMA: That’s a good boy.