Currently there are 267 charter schools in New York City. In New York State the charter ‘cap’ is 460, though the cap for New York City is 267 so as of right now, no new charters can open in New York City.
Charter school supporters often complain that the cap needs to be lifted or that some of the out of NYC charter slots could be given to New York City. But there are two ways that charters can get more students even without lifting the cap. The most obvious way is for charters to reduce their attrition rates. So a network like Success Academy has about 40,000 students right now. But about 75% of their students who start in kindergarten don’t make it to graduation. Success Academy could probably increase their population to 70,000 if few of their students weren’t on the official or unofficial ‘got-to-go’ list. The other way to evade the cap is for existing charter schools to expand into more grades.
Ember charter school is a K-10 school that currently has 568 students. They were recently permitted to add high school grades based, in part, on the school’s ability to raise test scores. If you go to their website you will see a very impressive looking graph:
The light green line shows the percent of their first cohort’s math percent passing the state test from grade 3 to grade 7. It went from 28% in grade 3 down to 23% in grade 4 and then again to 14% in grade 5 Then an amazing reversal occurred and in 6th grade they shot up from 14% up to 56% and the next year they had 82% passing in grade 7. It seems to be an incredible turnaround from 14% to 82% in just 2 years.
When faced with a miracle statistic like this, there are two questions that cross my mind. The first thing I wonder is how much of this growth is based on attrition. The second is whether they were able to replicate this success for their other cohorts.
For that first cohort who finished 7th grade in 2018, I found on the New York State data site that this cohort once had 60 students when they were in first grade. By the time they got to the miracle 2017-2018 year where they got 82% passing the math test, they were down to just 28 students. Here is a graph of their percent passing math and their cohort size on the same graph.
As you can see, the two graphs are practically mirror images of each other. When they were 3rd graders, 16 out of 57 was 28%. When they were in 7th grade, 23 out of 28 was 82%. So basically they got 7 more kids to pass the test.
I made a similar chart for the second and third cohorts. The second cohort had similar attrition, they went fro 71 students down to 37 between 4th grade and 7th grade but they did not get the 82% passing by 7th grade. They only got to 43% passing, even with the nearly 50% attrition.
The third cohort was the lowest performing of all. They had almost no attrition, keeping around 65 students throughout. They only had 6% of that cohort passing in both 3rd and 4th grade. And by 6th grade they were up to 23%, well below the district.
So just like so many other charter schools, when they can’t cheat by booting out their students, their test scores are nothing special. How they get permission to expand is definitely a scandal.