We now have quite a bit of evidence that certain urban charter schools are very effective. (Note: by no means does this mean that the average charter school is very effective.) The best evidence comes from looking at admission lotteries in which researchers compare outcomes for students admitted in the lottery to those who missed out. What’s nice is that the two groups of students are likely similar in terms of unobservable background characteristics.
What’s not so nice is that both the winners and losers are “special” in the following sense: the students and/or their families were motivated enough to apply in the first place. Maybe charters work well for children from motivated families but not for others?
New research, “Charters Without Lotteries,” offers some good evidence that certain urban charters work whether students are from motivated families or not. The researchers take advantage of a kind of “natural experiment.” A number of middle schools in New Orleans (plus one in Boston) were converted to charter schools under a plan in which students already in the school were able to stay in the new charter version without having to apply. In other words, these students were in without having to be specially motivated.
Students in the New Orleans schools were compared to similar students in schools that weren’t converted. The “grandfathered” students had better outcomes than students who remained in traditional schools. In Boston, the researchers could actually compare students who were grandfathered into the converted school with students who won a lottery to get in. The grandfathered students did as well or better than the students from the families sufficiently motivated to enter the lottery.
Here’s one of the authors’ figures for New Orleans. The dark line shows math results for grandfathered charter students; the lighter line is for comparable non-charter students. Things were improving in New Orleans for both groups, but scores improved much faster for the charter school students.
I think this is the first real evidence that charters can work for a broad group of students. A reminder though, the fact that particular charters (mostly “No excuse” schools) work well in a particular urban context does not mean that the broad spectrum of charters are similarly successful.