“The one thing I’d like to see controlled for is that public schools are required by law to take disruptive and low-functioning kids, and they are required NOT to track students into ability level classes.”
Ability level tracking is logical.
But of course, liberals are not logical. Ever.
Why not just have public schools for the losers and religious schools for the rest.
By “religious schools”, I specifically exclude Islam.
My wife, a high school level math teacher says tracking is so important in her field, and so obvious in her field, but that the true believers running education absolutely refuse to look at facts.
History probably doesn't make much difference if you track or not, but one level or another of student is going to be hurt if you insist on it in math.