Monday, November 27, 2006

Scores and class size

The Chicago Sun-Times reports the astonishing news that some of the highest-scoring Chicago public schools also have the largest class sizes:

Small, medium or large. What class size would you choose for your child? Today, in the second of two parts -- what may seem counterintuitive: Some of the best test scores are being racked up by Chicago schools with some of the largest primary class sizes.

If you're looking for a high-scoring Chicago public school, be prepared to accept larger class sizes in the early grades, just when some experts say smaller classes count the most.

The 25 highest-scoring schools in CPS average roughly seven more kids in their primary classrooms than the 25 highest-scoring suburban schools, or about 27 kids vs. 20, a Chicago Sun-Times analysis of state public school data indicates.

That's seven more kids in a CPS room just as children are learning everything from how to read to how to sit quietly at a desk and do classwork. Compared with the statewide primary average, it's roughly six more kids.

At top Chicago public schools, K-3 classrooms with at least 30 students aren't unusual. Meanwhile, many kids in top suburban schools enjoy the intimacy -- and efficiency -- of 16, 18 or 19 kids in a class.

Rising scores in some Chicago neighborhood schools -- among the system's most affluent -- have brought a rising tide of students, jamming classes to the point where some parents want relief. Even some of the city's most popular magnet schools have 30-plus classes, often because of the extra teacher bigger classes bring.

At first glance, the results at Edgebrook School, on the Far Northwest Side, seem to stand common sense on its head.

In 2004-2005, Edgebrook's sole first-grade room held a whopping 40 students. That year, the school posted the highest test score among the city's neighborhood schools, yet it had the largest primary class sizes in the six-county area. At least two of its tested grades that year -- third and eighth -- held 30 or more students.
At first glance this would seem to give ammunition to those who contend that class size doesn't matter. However, it would be a mistake to generalize from the cases reported above. The crucial element that allows large class sizes is the quality of the student body. Edgebrook School is a case in point. The school is located in an affluent area and peopled by students enjoying a high socio-economic status. This success could not be replicated in large classrooms filled with the disadvanted, many of whom suffer from behavior disorders. Such students need more intensive teacher attention.

Via Joanne Jacobs.


rightwingprof said...

Indeed, no generalization can be made with only several schools in one city. Another thing that could be going on: larger classes are less amenable to macaroni art pedagogy than smaller classes.

JohnL said...

One issue that isn't addressed by the size of classes is the qualities of the instruction that happens in them. Rightwingprof's comment hints at this. More specifically, if teachers with classes of 30 are faithfully employing evidence-based reading instructional methods, their students are likely to have higher achievement than the students of teachers with classes of 20 who are using let-the-darlings-discover-reading-according-to-their-own-natural-blooming-rates.

Class size does make a difference, though it's probably pretty small (until one gets to really small classes). I've posted about this on Teach Effectively! in an entry called What matters.