There's a significant shortage of teachers in the US & Canada, especially for math & sciences, so I'm not sure how we could realistically reduce class sizes in the short to medium term
Yeah, fair point. I guess from my perspective (my sister is a teacher at a charter school in Iowa that does have lower class sizes and much better educational outcomes) smaller class sizes seem like such low hanging fruit if the objective is simply to improve learning, not over-specify some testing metric.