Are demographics controlled for here? We know the proportion of foreign born has been increasing since the 70s, are these results attempting to remove the effect of non-native speakers?

>foreign born

Its probably more useful to distinguish between foreign educated vs born here.

Interestingly the last stats I remember seeing about ESL students is they tend to out-perform english students in a number of subjects depending on the age group, so factoring them out might lower the overall stats and show an even worse trend among native born english speaking American students.

There's another, more global research: https://www.afterbabel.com/p/the-edtech-revolution-has-faile...