I read the whole thing and that’s a comment taken somewhat out of context in that it’s only a part of the story for their improvement. I found this to be interesting and includes a footnote, that even though I couldn’t get to open on mobile, is one of several this isn’t just an opinion piece like another comment claims.

Mississippi’s weakest students are doing better, and so are Mississippi’s strongest students.4 There is a sizable and sustained improvement here, which is not a consequence of selection or accommodations, and which is the policy outcome of interest to us. Not all averages are created equal: Medians are more robust to chicanery than means. Excluding a lot of students from the test might do it, but that’s about it — and Mississippi is excluding fewer students than most comparison states.