Silly question

[Carol]

md:
> 
> Writing 101, you can't switch tense. <snip>

Carol responds:
You can when you're quoting from another book, in this case "History of Magic." In fact, if the book you're quoting is in present tense, the quotation must be in present tense.

Writing 101: Quote exactly or use brackets or ellipses to indicate alterations.

Since Hermione is reading aloud from the book, she has no choice but to quote exactly.

Carol, noting that dialogue is also in the present tense most of the time