The funniest implication here is that the student's writing skill isn't expected to improve.

I was just asking my partner who’s a writer if it would even be fair to train a model based on a student at Nth grade if the whole point is to measure growth. Would there be enough “stylistic tokens” developed in a young person’s writing style?

Personally, I feel mildly embarrassed when reading my essays from years prior. And I probably still count as a 'young person'.

That said, there's no need to consider changes in years when stylistic choices can change from one day to another depending on one's mood, recent thoughts, relationship with the teacher, etc.

That's why I've always been a little confused about how some (philologists?) treat certain ancient texts as not being written by some authors due to the text's style, as if ancient people could not significantly deviate from their usual style.

Surely you could continuously add data about their latest essays to the model, meaning any gradual improvements would be factored in?

> first day of class, write a N word essay

Initially I thought you meant having the student write an essay about slurs, as the AI will refuse to output anything like that. Then I realized you meant "N" as in "Number of words".

Still, that first idea might actually work; make the students write about hotwiring cars or something that's controversial enough for the AI to ban it but not controversial enough that anybody will actually care.

There are also some countries that don't fetishize cheating this much so perhaps they will just continue not caring.

> first day of class, write a N word essay and sign a release permitting this to be used to detect cheating

Why once? Most students need writing skills more than half the high-school curriculum.

Arms race are not really an issue, you've managed to make your student work, one way or another.

> upside: this also helps detect students who are getting help (e.g. parents)

Downside: it also likely detects, without differentiation, students whose writing style undergoes a major jump because of learning, which is, you know, the actual thing you are trying to promote.