Does class size matter? School districts think so: that's why they're keen on small classes. Parents think so as well. That's why they pay through the nose to send their youngsters to private schools that boast small classes.
The researchers are split. The gold-standard study -- the Tennessee STAR project, carried out in the 1980s -- showed that youngsters in small classes, with 13 to 17 children, did better academically than those in standard classrooms, with 22 to 25 pupils. But the differences were relatively small and arguments have raged ever since about whether there are better ways to invest education dollars.
Radically different approaches to teaching and learning change the equation. They demonstrate why small classes matter.
When the Tennessee study was carried out, students were typically taught in a single group, sitting in neatly aligned rows of chairs. In that kind of classroom, you'd expect the effects of reducing the number of students would be modest. Youngsters in the bigger classes might get a few less opportunities to recite and teachers might pay a little less attention to their written work, but in the life of the classroom, that's not such a big deal.
Since then there a pedagogical revolution has taken place. More and more, students are grouped in class on the basis of ability, with different alignments for reading and math. They're also grouped to encourage collaborative work and to discourage cliques. What's more, students are likely to spend a chunk of each day rotating through different activities -- on one day four or five of them will be absorbed with computer-generated problems, while another group is doing hands-on problems and a third group is building diaramas.
This kind of teaching started in elementary school; the approach is working its way up the ladder, to middle and high school, because teachers see that it make a difference. Not only does it demand more of teachers, in terms of class preparation, it also requires much more contact between the teacher and each of the groups. The teacher is constantly moving from one reading group to another, checking on different math problems, helping out with a variety of projects, seeing how well students are doing on the computer or discussing which book they would enjoy most.
In that kind of class, the number of students makes an enormous difference. Imagine a typical class hour in which students are working on projects in groups of four: with 16 students, the teacher can spend 15 minutes with each group; with 24 students, the amount of time drops to 10 minutes.
As someone who has spent a lot of time crouching in classrooms, I've seen how much difference an additional five minutes of close attention can make, especially for students who arrive at school behind the curve. And where classes number 30 or more, as is increasingly the case, project-based teaching becomes nearly impossible.
The sea change in teaching makes the old studies obsolete: the researchers should go back to the drawing board. Meanwhile, school districts harbor no doubts that class size matters. That's why, as the New York Times recently reported, San Diego is struggling, in the face of budget cuts, to maintain classes no larger than 17 for kindergarten through second grade. From everything we know, that's the right strategy.