I present to you detailed breakdowns for the 10th grade.
The biggest difference I see, compared to previous grade levels, is that the fraction of black students used to be higher in the regular public schools at grade 10 than it was in the charter schools.
I know for a fact that membership in the 10th grade for testing purposes is something that school administrators can and do mess around with: students are sometimes held back and then skipped over the 10th grade entirely if their scores might embarrass the school…
Here we see a general rise over 4 years. Are they choosing their students better than the regular DC public schools? Are the charter schools really teaching better? Or teaching better to the test? Who knows? This is the only grade in which the trends are markedly different in the charter schools than in the regular public schools.
Here it gets interesting. While the pass rates for 10th grade black charter students increased from the previous year, they are still lower than they were 2 years ago; but the pass rates for ALL charter students have been going up fairly steadily. What’s going on? I have no idea.
As promised, the big surprise here is that the fraction of the regular-public-school 10th grade class that is Black and non-Hispanic used to be higher than the corresponding fraction among the charter schools. Why the population has shifted in this way is unclear to me, but I suspect it has to do with purposeful manipulation of which students are selected to take the DC-CAS at the 10th grade.