Gary Rubinstein, teacher and blogger, reviewed state data for Eva Moskowitz’s Success Academy charter chain. SA has been widely acclaimed for its high test scores. But Gary found that the attrition rate was astonishing. If low-scoring students leave, it boosts the overall scores.

Gary knew that the overall attrition rate was high but was surprised to see how high it is for students who enter ninth grade.

Over the years I’ve tracked the attrition at Success Academy. They are a K-12 program and I’ve found that generally when I compare the number of kindergarteners entering the school with the number of 12th graders that graduate 13 years later, they lose approximately 75% of their students over the 13 years.

Success Academy has argued that losing 75% over 13 years isn’t actually that bad since it equates to about 10% attrition per year, which is what district schools also have. One flaw in that reasoning is that district schools fill in those 10% of seats each year while Success Academy stops ‘backfilling’ in the 4th grade. Another problem with comparing attrition rates from Success Academy to district schools is that a student can pretty easily move from one district school to another and those schools won’t be all that different. But for Success Academy which are supposedly the best schools in the country, it is a major life change to leave Success Academy for a district school so if they really are as good as they say, you would expect their attrition to be less than the 10% per year that district schools have.

I recently got some data from New York State that puts the attrition of Success Academy in a different and scary context. Since Success Academy is a K-12 school and you can’t get in after 4th grade, any student who makes it to 9th grade there has been at the school for anywhere from 5 to 9 years. After making it that long, the last four years should be pretty easy. It’s like running a marathon and getting to the 25 mile mark, of course you are going to finish the race. But some new data I got reveals that this isn’t the case with Success Academy. In general, only about 60% of the students who become 9th graders there eventually graduate within 6 years. And with certain subgroups it is a lot less than that….

This data is really scandalous. Have you ever heard of a school that sheds almost half their students in a four year period from 9th to 12th grade even though those students have been in the school since kindergarten or maybe 4th grade at the latest? A question I wonder is why do so many students leave the school so late in the game after succeeding there for so many years?