That afternoon is AP English, which Isabella attends. Partway through she is excused to the restroom. She doesn't bring her notebook along, although she does close it on her class notes - without so much as putting a bookmark between the oddly parchmentlike pages - before she goes.
Arthur lazily runs his fingers over the page-end of the notebook. He whispers to Suze, "This is really odd paper. Wonder how it was made?"
Arthur passes it to Suzy, who opens it up to the first few pages.
The notebook falls open to detailed notes on a bookbinding course Isabella apparently took once. There are what look like slightly filtered photographs, stamped right into the pages as though they were inked there.
And then turns to another page.
Four thrones, three empty and in one of them a girl, who looks just like Isabella but a few years older, in queenly raiment with scepter and crown.
"She looks like Isabella. Maybe she has a cousin? Who does really, really thorough fantasy SCA, and made a fancy printed book with pictures and notebook pages for Isabella. Which has notes written in it before some of the pictures."
Here is Isabella mounted on a griffin.
Here is Isabella addressing a giant.
Here is Isabella and a centaur doing archery side by side.
He'll turn a few pages back and forth to see if they stay the same. But he's still going to close the book afterwards.
A map, pasted in in index-card-sized installments from some other source, of a place that seems unlikely to exist on the geography teacher's globe.
A to-do list with items like "expecting messenger from Archenland" and "consult Mr. Tumnus about rescheduling appointment with representative from the winged horses".
English proceeds, mostly without Arthur and Suzy paying any attention to it.
Isabella comes back from the bathroom. She lets her notebook drop carelessly open; it displays English notes and she adds to them diligently.
At a spare moment a few minutes later, Arthur turns to Isabella and says "I'd like to hear more about your daydream story sometime. With the unicorns and fauns and all."
"No, but they're in the book. The paper was odd and we didn't expect... any of that."
"Isabella," says the teacher. "Is there something you want to share with the class?"
"No, Mrs. Williams, I'm sorry," says Isabella, clutching her English notes.
"It was your English notebook, it didn't seem secret! And I put it down as soon as I figured out the pages didn't stick to one thing."
"I opened it. Sorry. We just saw some stuff about making books, and a couple pages of pictures."
"I use it for things besides English. Never open it again," hisses Isabella, and then she returns her attention to the lecture.