There is a similar effect in parts of SFUSD where some of the schools with more poor students are bucking trends: https://sfparents.org/sfkidscantwait/

(SFUSD overall has something like a 10% poverty rate and a 3% marginally housed population, so I think the comparison is fair)

In our school, we saw a lot of outdated teaching materials - we got our kids hooked on Alphablocks - a BBC funded children’s education program that teaches phonics, because it seemed like there were no explicit classes in phonics. The debate over phonics is settled, they work - I understand the situation here is improving.

The math curriculum has improved too, they are adopting techniques from Japan, but I suspect the limiting factor there is teachers’ math discomfort.

In the end it’s been the parents holding the school system and elected officials accountable that has spurred change. I bet behind the great numbers in Mississippi is a sea of under-appreciated moms.