- On the evening of her sixteenth birthday Septimus and Thomasina dance
- They kiss
- She invites him to her room, to de-flower (ugh, awful word) her
(This is where the play ends)
- Thomasina leaves a candle burning, waiting for him to go to her
- He doesn't
- The candle catches the house on fire
- She burns to death
So, poor Septimus is left in an awful mental / moral position, where by doing the "right" thing, and not taking (awful word again) his pupil's virginity, he's accidentally caused her death. He goes (possibly) mad, and spends _the rest of his life_ living in the fake hermitage, running the iterations of Thomasina's algorithm by hand.
It's so beautifully tragic, and Stoppard leaves it there as a trail of breadcrumbs for his readers / audience to suss out on their own. I love it.
When I got out of the education game the Online Everything push was just beginning. I'm kind of glad I missed it, to be frank. As techy as I am, as a teacher I really grooved on the immediate, in-person nature of a classroom environment. I never put any of my classes online, and (though not taking anything away from those who have found success doing it) have no desire to teach like that.