Ups, Cakes did it! She is the source of all problems with education. Problem solved.
The word "thick" is so unpalatable, it puts the moose on the table. Let's switch to some obscure euphemism. We don't think they are stupid, we think they have low processing speed.
If processing speed is so important, why nobody measures it? Even
in cognitive assessments for children with SEN, low processing speed is rarely measured. The assessments done by EPs always involve some sort of IQ measure like Wechsler WISC, but it does not even have a part for processing speed as such.
CAT tests are actually used to set, along with SATs. CAT tests don't measure processing speed either because it is beside the point, but is conveniently obscure so helpful to dodge the argument.
Noble, the French and the Finns, the Asians, and the whole world also have a range of abilities. Yet, they educate bigger proportion of their population to better outcomes without sets. Do you agree with the statement:
"No bigger fraction of Brits have low ability, than the fraction of the French (etc) who have low ability, so equal percentage of Brits and of the French should be able to attain equivalent level of knowledge / qualifications"
Why don't you engage with this argument?