I don't know, but it's odd. Like, even in my geometry class which is supposed to be for sophomores, it's mostly freshman and juniors, a couple soph, a couple seniors. It's odd.
In my class there's loads of Jrs. and Srs. because they're homeschooled and just decided to take HS for 2yrs or so for certain subjects. . .mine, is oddly, the only one like that. . .it's . . . different. They're brilliant in that class, though.
Ahh. Mine.... English and Bio are primarily freshman. But we have a couple of soph/juniors in bio, because it's honors so apparently you can take that after regular bio, though I don't see why you wouldn't just do AP....