If there is only one classroom, there are no options for students and no ability to mix students. And we should continue. Large schools provide a wider spectrum of programs and have more flexibility. The learning environment has been a concern, that small schools have a better climate. There is no huge effect on student achievement.
Large schools can structure into small schools within a school.
Nationally, some elementary schools are in the thousands. We are not talking about that. Our notion of a large school is 300-500 at one site. This could be an alternative plus a neighborhood school. That counts as one school with one principal.