The biggest factor affecting school budgets is class size-- smaller classes means more teachers, and schools spend most of their money on teachers. So the obvious question is "how small is small enough." Obviously one-on-one tutoring with a teacher is the best way to learn, but there's a cost-benefit tradeoff we need to figure out.
Happily, there's bunches of research on class size and student achievement. There's a nice summary of the research at the US department of education website. From that summary:
A consensus of research indicates that class size reduction in the early grades leads to higher student achievement. Researchers are more cautious about the question of the positive effects of class size reduction in 4th through 12th grades. The significant effects of class size reduction on student achievement appear when class size is reduced to a point somewhere between 15 and 20 students, and continue to increase as class size approaches the situation of a 1-to-1 tutorial.and:
...reducing class size is especially promising for disadvantaged and minority students.There are 23 kids in Robin's kindergarten class... hmm. Not good. But there's a full-time teacher's aide helping out, so maybe that's like having half that number.... except that there's a study that showed that teacher's aides don't help student achievement.
Reading through the 2007 Amherst Regional Schools Budget Guide, I see (on page 10) that average class sizes for the high school are between 20 and 23 students. Since the research shows that class size definitely matters in grades K through 3, and since it also shows that there's little difference between a 20-student class and a 30 student class, maybe we're not spending our money wisely.
There's probably politics I'm not aware of (and probably other barriers-- like lack of classrooms in our elementary schools), but it seems to me we should increase class sizes at higher grade levels, and spend the money saved to pay for more K-3 teachers.