OK, I didn't care to investigate that much, so I'll take your word for it.
But what he's writing on that window is BASIC calculus that we learn in highschool here, in Romania, one full year before we even go to University!
When I was in the 7th grade, a colleague of mine and her sister, who was one year older than the two of us, left for Canada.
The little one entered the 10th grade and the older one in the 12th grade.
We were hearing that the older one was actually schooling her math teacher there, in Canada. Haha! (true story, not bullsh!tting in any way)
Edit:
And one more thing (unrelated to this specific kid): don't underestimate the power of memorization of 12 year olds.
In the 7th grade (13yo) I participated at the Biology Olympics, having learned from University grade books. I narrowly missed the 1st place because at one question I wrote a very short essay explaining why their question was dumb and no answer was correct. (I was a legend that day
)
In the same year I went to like... 4 different Olympics and at each of them I got pretty high in the hierarchy.
Did I understand the things that I had learned? Of course I did, but without the huge memorization that I did I wouldn't have gotten anywhere.
And I wasn't even the smartest kid, let alone a genius. (actually, I as the smartest kid in my school, goddamit, but still no genius)
Anyway, props for the kid in the OP.