Is that what you're saying?
The most obvious case of this is comparing private vs public schools, where the private schools can be selective and kick out anyone who doesn't perform or they don't like, but the public schools have to accept everyone by law.
Obviously failing anyone who cannot read from getting to 4th grade will greatly improve 8th grade reading scores.
What we care about is the level of achievement by a given age. To determine that, we need to be comparing states using standardized tests given to age groups, not grade levels. It is fine to hold students back, if we think that will do them more good than advancing them. But they still need to be tested the same way as their age group if we want to do a meaningful comparison between states.
See this example of a paradox that applies a lot in educational settings: you can raise the average level of two classes just by shuffling students from one to another:
The data point is the number of 3rd graders failing. If you insist in filtering out those 3rd graders, limiting your analysis to the subset of kids who didn't failed does not represent a success story. It represents an attempt to arbitrarily remove inconvenient data points to portray a false idea if success.
Even if we assume that's the case, that's not the problem.
The problem is that the school system fails to provide the necessary and sufficient services that would prevent a statistically significant number of 3rd graders from being held back. Feeling the need to hold kids back is a symptom of the problem, not a solution.
I strongly suspect that Mississippi should be allocating more resources to education. But this is a political problem and the schools have nearly no say in whether the legislature does or does not increase funding.
So. Do we close down the schools and wait until it is resolved?
Or do the schools do the best they can with the resources they have? Do you have evidence that placing kids in the most skill-appropriate classroom is a worse use of available resources than placing them in the “correct” classroom based on age or previous cohort?
"Ton of spending" are weasel words. "Not a ton of results" is already the problem.
If your school system fails to teach kids how to read after 3 years, this is a school system that fails at it's primary and most basic responsibility. These third-graders are not the problem, they are the canary in the coal mine.
Advocating for holding back third graders and expelling underperformers is a kin to advocate for getting rid of canaries because they are a nuisance when assessing health and safety.
I never disagreed on this point.
Now what? Every morning, kids wake up a day older. Is there a way to hit pause so you have time to go in and fix it?
If a school system is designed so that the average kid in 3rd grade is expected to be in 4th grade the following year, the fact that a statistically significant subset of kids is not able to meet that bar is a sign that the system is failing those kids.
What's the goal here? Is it to get pretty metrics by filtering out the failures, or is it to provide an effective education to all kids?
Because I bothered to look it up. In the last few years, Mississippi has been holding back between 5-10% of it's students.