October 4, 2012; Source: GFBrandenburg’s Blog

We’ve seen an increasing line of reports that suggest that charter schools aren’t always clean-up hitters when it comes to student performance, contrary to the image conveyed by promoters and advocates of charters and broader strategies of school privatization. G.F. Brandenburg is a retired math teacher who seems to like applying math (plus common sense) to publicly released data, such as recently released school performance data in Washington, D.C.

He starts, naturally, with data on the proportion of students proficient in math in regular public schools versus charter schools. In D.C., fifteen out of 117 regular public schools—13 percent of the total—can claim that 80 percent or more of their kids test proficient in math; only four out of 70 charter schools—six percent—can claim the same. For reading proficiency, a similar pattern holds. Fourteen regular D.C. public schools—12 percent of the total—have student bodies with 80 percent or more proficient; only two out of 70 charter schools—three percent—have 80 percent reading proficiency scores.

Might that be due to the improbable prospect that the regular schools are somehow gerrymandering their admissions and ditching responsibility for teaching low-achievers? Brandenburg shows that the D.C. public schools are not only getting high performance in reading and math scores, but that they are also taking on more than their share of low-achievers: 15 or 16 (depending on whether you’re referring to math or reading) percent of public schools have test scores where less than 20 percent of the students are proficient; the comparable numbers for charter schools with less than 20 percent proficiency in reading and math is three percent.

Brandenburg notes that the DCPS data doesn’t cross-tabulate these proficiency numbers in schools by gender, race, ethnicity, proficiency in English, special education status, family income, or grade. As a result, we would bet that Brandenburg’s interpretation of the DCPS data will generate positive remarks from observers who suspected that the charter schools have been vastly overhyped by adherents such as former D.C. Schools Chancellor Michelle Rhee and negative commentary from charter school advocates who believe that the data do not tell enough of the story.

At least in D.C., however, it isn’t a small sample. There are a large number of charter schools operating throughout the city. Charter schools have to begin owning up to student performance data that may not match their promotional materials to ask why there is a gap between the public image and the actual performance of privately managed schools.—Rick Cohen