Aug 23, 2009

DCPS Elementary Schools Outperform Charter School Counterparts

Guy Brandenburg, a retired DCPS math teacher analyzed the DC-CAS scores raw data and released the press release below on August 18. Guy reported that DC public elementary schools outperformed their charter school counterparts while the situation was almost exactly reversed at the secondary level with charter schools taking the lead. I did want to share portions of Guy's analysis with my readers. If you are desirous of reading the document in its entirety, please send me an email c/o or leave a post on my blog with your email address.

Situation Almost Exactly Reversed at the Secondary Level

"The results from last year’s DC-CAS flatly contradict the media-spread ‘wisdom’ that public charter schools always do better than regular urban public schools. In fact, regular DC public elementary schools out-performed the charter schools on the 2009 DC-CAS in 11 out of 14 categories. Strangely, at the secondary level, the results were almost exactly the opposite: in 12 out of 14 categories, the secondary charter school students scored higher.

These results come from a mathematically simple, but tedious, calculation of the averages of the percentages of students in the various subgroups who were deemed 'proficient' based on their scores on last spring's version of the DC-CAS (Comprehensive Assessment System) exam, which is taken by all DC public and charter school students in grades 3, 4, 5, 6, 7, 8, and 10 under the No Child Left Behind act, or NCLB. The computations were done by this writer by cutting and pasting the data into several Excel spreadsheets, separating the regular and charter schools, and taking averages of the averages provided for each group given in the data on-line.

On the elementary level, the regular public school students outscored the charter school students in the following eleven categories:

In both math and reading, the entire schools in question (about 48% versus 38% in math, and 48% to 45% in reading): in both math and reading, among the economically disadvantaged (meaning, those eligible to receive free or reduced-price lunches), by about 43% to 37% for math, and 43% to 42% in reading; in reading only, among the educationally disabled (also known as special education students) by a score of 32% to 26%; in both math and reading among LEP-NEP students (that is, students with limited or no proficiency in the English language), by scores of 55% to 48% in math, and 47% to 43% in reading; in both math and reading among black students, by scores of 46% to 37% in math, and 47% to 45% in reading; and in both math and reading among white students, by scores of 93% to 85% in math, and 92% to 91% in reading.

The only three categories where elementary charter school students did better were these:

In math only, among special education students, by a score of 29% to 28%; and in both math and reading among Hispanic students, by scores of 56% to 53% in math, and 49% to 47% in reading.

On the secondary level, the situation was almost exactly reversed......"

Posted by The Washington Teacher, press release courtesy of Guy Brandenburg


Anonymous said...

Buzzer blew,games over ! End NCLB !Way to go !

Anonymous said...


Be careful. You might ruin Fenty, Rhee, Duncan and Obama's day. You are destroying the NCLB MYTH.

Mr. Potter said...


Let's just remember the last sentence of the analysis. "On the secondary level, the situation was almost exactly reversed......"

I don't work in a charter school, and I want to see DCPS cleaning the charter's clocks, but I don't think we should break out the champagne just yet.