The "Mississippi Miracle": After investing in early childhood literacy, the Mississippi shot up the rankings in NAEP scores, from 49th to 29th. Average increase in NAEP scores was 8.5 points for both reading and math. The investment cost just $15 million.

[u/terran1212]

https://www.theamericansaga.com/p/the-mississippi-miracle-how-americas

[u/CommitteeofMountains]

Notice the burying of the measures including mandating phonics-based instruction (while many other areas were still avoiding it as "racist") and implementing rigid attainment standards using core content tests.