What that does NOT say, however, is that the sky is the limit.
From a practical standpoint, for example, there is simply NO WAY for a teacher to teach 150 students in high school geometry/English/Biology the way that s/he would teach just 30 or 40 of them.
So there are shifts that occur toward less effective pedagogical practices, toward less individually-appropriate instructional strategies, toward less flexibility.
It's also true that when you reach some class size, there is a sharp DECLINE in quality of educational experience, too.
So while it may be that "15 students in calculus is no better than 25," for example, that is not the same thing as saying that 50 students in that class is just as good for the students as 20 would be.
It's not a logically symmetrical argument, the way that it's researched.
It really angers me that policy-makers and voters tend to misinterpret that data on that score.
School consolidation is the big deal here-- because it, too, saves a lot of money. Heck, there are a million ways to save a buck in operating a school district that serves 10K students, probably. After all, if the students just put in six twelve hour days each week from March through the end of September, that would certainly work to generate the requisite number of instructional hours each year-- and natural lighting is at its peak, so operating expenses are lower, etc.
What the research does suggest, however, is that smaller schools are just plain BETTER for kids, and that the effect is pretty pronounced through middle school, and still measurable even in high schools.
That's not to say that CLASS sizes need to be small in secondary-- just, as noted above, maybe "manageable" in light of the subject, grading load, etc. But I sure get tired of seeing how many ways politicians in my own state can twist this data in order to squeeze a few more pennies out of the Ed budget each year. {sigh}
