And our K-2 elementary school was 1200 kids. Our district then goes 3-4 (800), 5-6 (800) and high school (I'd guess 1600). And there is only in class differentiation until 6th grade when an honors math course is offered and 7th grade where there's an honors algebra course and science Olympiad - and I suppose in-class differentiation. At some point, maybe 7th grade, they start to cluster the kids more than 1-2 in every class. So interesting how the schools vary.