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Obligatory Sold a Story podcast link.
I can't help but feel that a lot of this is deliberate, the end result of decades of dismantling the public education system to further divide kids into the upper class in private schools, religious fundamentalists in home schooling, and everyone else abandoned to keep the population uneducated and in worse economic precarity.
Somebody please tell me that the kids are alright 
I know it’s kind of a given because
but the OP of that thread is spouting some reactionary nonsense in those edits.
Also, it feels like there’s an implication in the original question that kids should be being held back. It’s generally agreed upon at this point that retention is almost always detrimental. Kids move up with their peers and then they get individualized intervention depending on their needs.
Just the same old lack of class analysis. Quick to blame parents for failing their kids without stopping to ask why they aren’t teaching their kids to read.