Smaller class sizes are not the answer to creating better schools. I've been in classes of 5 students where the teacher had no control and we ran the room. I've also been in classes of 60 where the teacher was in full command and we learned our lessons. All else equal, class size might have an effect on student learning (or performance or any other tangible measure). However, every dollar spent on accommodating smaller class sizes is a waste. That money could be put toward hiring better teachers. How do you get better teachers? You pay them more. Right now, K-12 teachers (at least in Florida) get paid peanuts. You get people who either 1) love teaching, or 2) couldn't get a better job somewhere else so they settle for teaching. To improve schools, you want to eliminate the Type 2 teachers. Keep the Type 1s and pay them more if you can. But, we need to recruit people with skillz who have jobs in other sectors precisely because schools won't compensate them adequately to teach.
In fact, schools may be able to save money by hiring better teachers. If they trim the fat, aka shitty teachers, and replace it with lean meat (the rockin' new hires) then they can increase class sizes. This will raise the student-teacher ratio and schools can use their space more efficiently. No need for new construction or acquisition of new land. Just out with the non-hackers and in with qualified instructors. Their contracts should make pay relient on performance: a weighted average of student evaluations, peer and administrative evaluations, standardized test scores, and workload.
Students who learn better in an intimate setting can go to office hours. F*** smaller class sizes.