Why are teachers unions warning about expanding class sizes even though the child population is declining in Los Angeles and other parts of California? The Golden State has a history of hawkishness on class size, but the intuition that class size strongly influences learning outcomes is not well supported by evidence.
"Class size is the most expensive, least effective intervention you can make in our education system," said Marc S. Tucker, president of the National Center on Education and the Economy, back in Aught-Six. This month, the Brown Center on Education Policy at Brookings seconded that counterintuition: "Class-size reduction has been shown to work for some students in some grades in some states and countries," says a Brown Center study [pdf], "but its impact has been found to be mixed or not discernable in other settings and circumstances that seem similar. It is very expensive."
These assertions are far enough outside mainstream discussion that Los Angeles public school teachers still speak broadly about class size and student/teacher ratios – as my buddy does (with some alarming math) at the 1:55 mark in this Reason TV video:
Even if we posited the primacy of class size in edumuckation, the fact remains that class size is, at worst, flat over the last decade.
Education Data Partnership indicates Los Angeles class sizes declined for at least three straight years through 2009, leaving per-class population below where it was in 2000. The California Department of Education shows the L.A. Unified School District's student/teacher ratio inching from 21.4 in 2006 down to 21.3 in 2010. Despite these trends, the not-enough-teachers story is one of journalism's enduring evergreens.
Caveat: Average class size numbers can be deceptive. There are grade-level mandates on student/teacher ratios in California, and while the general trend is that class sizes increase in higher grade levels, there are plenty of exceptions. But one part of the class-size equation – the overall number of students in the system – continues to get smaller.
(Disclosure: My experience of LAUSD is that "open enrollment," a magical system in which you can take advantage when a more attractive school fails to meet its student population numbers, makes for a more usable school system than the district's horrific reputation and parent price tag of $0.00 led me to expect.)
Why are student numbers shrinking? Los Angeles County's declining child population has been a low-wattage news story for some time. These photos from a nearly empty carnival that blocked my route home yesterday illustrate the plain numbers. The child-shortage scare has gone through various iterations. At one point it was described only as a decline in minority children, but now the breathless phrase of choice is "mass exodus of young children."
Could that have anything to do with a broader exodus from L.A.? In this disturbingly chirpy blog post, County Geographic Information Officer Mark Greninger notes that overall L.A. population is flat or barely higher over the past decade.
I find it hard to get exercised over contemporary class size figures, which are below my own student/teacher experience in the days of hornbooks and slide rules. I didn't go to school in California, however, and it's not easy to get historical class size data for the state.
If the declining population trend turns out to be real, it will be something new in L.A. County history. There's still some truth to the belief that a new crop of starry-eyed youngsters gets off the bus every day in Hollywood, but inbound migration may not save L.A. this time, because U.S. geographical mobility continues to fall. According to the Census Bureau, American mobility is more than a full percentage point lower than it was when Alison Stein Wellner's Reason story "The Mobility Myth" came out in 2006.
But a falling population does mean fewer students in schools. Even teachers can't lie about that. The two myths of class size – that it correlates negatively with student achievement and that classes are getting bigger – need to be retired.