Of PK Diffenbaugh and the trick of charter schools

The happiness and positive atmosphere was palpable. Tuesday night, at the board meeting of the Monterey Peninsula Unified School District, the exuberance was such I thought I'd been transported to the Happiest Place on Earth.

Why not? Daniel PK Diffenbaugh seems like a good guy. He has good answers for everything. Miracles appeared to have been performed at Sacramento High, the charter school where he worked for five years. Like Diffenbaugh likes to point out, the achievement gap was closed during his tenure, the school saw an increase in the Academic Performance Index (API) 582 to 778 and the state ranking increase from a 2 to a 7. Students meeting California college eligibility increased from 35 percent to over 80 percent. Over 75 percent of graduates were accepted to four-year universities including Stanford, CAL, and MIT.

I was ready to join in the celebration. Then I was reminded by an alert reader of a trick that charter schools are often accused of doing to mask their performance and make it appear better than it is. 

First of all, let me remind you of a complain I hear often regarding charter schools. The reason why students often seem to perform better than in regular public schools, it's because students who attend charters are those already better equipped for academic excellence: their parents are more aware of the education system, they're bound to be more involved, thus pushing their kids on a path to success.

But there's another complaint I've heard about, and in some cases, amply documented with reports and stories.

That charter schools inflate their academic success by pushing out poor performers  -- they skim from the top. They appear to have closed the achievement gap, increase college entrance, etc., by getting rid of students who don't perform up to par. Education historian Diane Ravitch often blogs in the issue. You can find one of her entries here.

So, what does this have to do with PK Diffenbaugh and Sacramento High? I don't know yet. But I did a little digging and I found something a bit alarming. In the 2004-05 school year -- the same year when he began working there -- the school had 1,692 students enrolled. When he left in 2010, there were 960 students.

For the sake of argument, let's pretend the class of 2006-07 -- when PK was already a principal -- had its student population equally distributed among all grades. By then, it was 1,147 students in the entire charter -- or about 287 students per cohort. By 2010, that would have been 240 students per cohort -- or a 16 percent, four year drop out rate, again, if the students were equally distributed among grades.

Again, I don't know if that was the issue here. But losing more than 732 students in five years, when charter schools are growing everywhere seems a bit concerning.

I'm going to have to do more digging. Stay tuned.