https://www.nytimes.com/interactive/2017/12/05/upshot/a-better-way-to-compare-public-schools.html
Basically, the article compares public school districts on how much improvement students achieve from 3rd to 8th grade.
For example, both Chicago and Milwaukee 3rd grade students are more than a grade level behind the average. But Chicago 8th grade students have improved to nearly average, while Milwaukee 8th grade students have fallen even further behind.
Meanwhile, the Anne Arundel County 3rd grade students start out more than a grade level ahead of the average. But 8th grade students there have lost much of their advantage to be less than a grade level ahead of the average.
The article does let you put in public school district names to see where specific ones of interest to you stand in terms of 3rd grade performance, 8th grade performance, and growth between 3rd and 8th grades.