Honesty, I don't have a single clue on how she could've noticed in like, under half a second to everyone but the entire memory to Sensei making it longer, and Nodoka somehow noticing (maybe something else than noticing) during that.
Nodoka seems very observant, so even something like Sensei's eyes glazing over would have probably been enough for her to get an idea that his mind went somewhere.
She later seems to be considerate enough to save something about Ami, that she thinks will affect Sensei, for when she thinks he can handle it:
So, she at least thinks she's got a grasp on Sensei's mentality.
The future Nodoka Ami plot is something I'm definitely looking forward to. She seems to be waiting for Ami to return to school and for Sensei to return to "normal", then she'll probably continue stalking Ami:
I mean, given that she knows what she knows - could be less supernatural and just that she understands why Ami won. Or maybe she realised just then (and the whole Sekai, Akira being the Boy, this fucking blanket, and Ami's relationship with him clicked).
Nodoka was probably around since she hung around Futaba, but like quite a few of the girls, she was going to the school that got swallowed at the beginning of Chapter 2, which is definitely something that hadn't happened before from Maya Prime's point of view.
If that never happened, Nodoka, Noriko, and Touka, etc, all wouldn't be in Sensei's class. Neither would Yasu. So, it's likely something supernatural was involved in that, and them being where they are, now. Something seemed to want the Nakayamas and Tsukiokas around Sensei.
Yasu also seems to be getting interferences and manipulated by something other than HOPE:
Frankly, Pareidolia sucks, but this "the world itself" seems to be the thing to watch out for. It may be manipulating Yasu, Makoto, and Nodoka at least:
"The world itself" also does not seem nice:
World also translates to Sekai, btw. So, the main Sekai roaming around, may be this thing, and Sekai seemed to imply she was up to something, back in Chapter 2:
There's also how Maya Prime was apparently experiencing, right from the start, Upside Down dreams:
Which were apparently strange to her, implying they were different than usual, and would imply something has been altering this timeline since the start.
Overall, some main notable differences in Chapter 1 before the school was swallowed, seem to be:
- Yumi stopped Sensei from erasing himself in static.
- Ami was convinced to become a Maid.
- Maya was given that green scarf.
Sekai's shadow showed up in the event that led Ami to becoming a maid:
(Ami's Chapter 1 'Cute Girls and Stuff' Event. Which led to her next Event 'Divergence')
And The Shapeshifter/Himawari was the one who sold Sensei the scarves:
(Chapter 1 'Stray Cat' Main Event, and Chika's Chapter 3 'Rough Cuts' Event, revealed the Shapeshifter's involvement.)
These events also took place at the Mall which seems to be Pareidolia's territory based off the 'Amy' Happy Event mentioning the Pareidolia Mall, and the Mall suddenly being renovated in Spring/Currently.
Something has definitely been manipulating things in the background.
