One of my (perhaps unsolvable) professional concerns is the large number of students who ace high school but flounder once hitting the higher academic expectations in college. This particular article was written by a student from Washington, DC, but it really could’ve come from anywhere.
A major contributing cause (though not the only one) is that the high-stakes tests that high school students take at the end of the year does not even come close to measuring college readiness. If I could wave my magic wand, I would assess the effectiveness of high schools not only with high-staking testing but also with graduates’ GPA in core classes during their freshman year of college.
Mean Green Math 
In theory, it’ a good idea. In practice, many colleges publish the grade distributions of each professor’s courses. That means students can go shopping for an easy A when they’re registering. Even if you could standardize your assessment by only comparing students who attend the same school, the results would be close to meaningless.
I agree that a simplistic formula like “75% of freshmen who graduated from High School A passed Precalculus statewide, compared to only 60% of freshmen who graduated from High School B” is not very helpful. There are several variables that need to be controlled, including (but not limited to) the overall grade distribution of the instructor, the institution, and the course.
Still, this strikes me as a much simpler assessment problem than those encountered in another field of extreme national importance: baseball. Sabermetricians have devised multiple ways of measuring the quality of professional baseball players, such as the VORP (Value Over Replacement Player), that have entered the vernacular of sports fans thanks to Billy Beane, Moneyball, and the mid-90s success of the Oakland A’s.
Twenty years ago, sabermetricians were generally regarded as benign if eggheaded crackpots, as they simply used different techniques for analyzing the millions of statistics that arise through the course of the game. (My running joke is that baseball is the second-leading cause of statistics in America.) Now, every team in Major League Baseball relies on sabermetrics as well as their traditional methods of scouting, and these techniques have expanded to other sports as well.
In my opinion, educational assessment is approximately where baseball was twenty years ago, as there are plenty of statistics that are naturally generated in the educational process and which could be analyzed with novel techniques instead of relying solely on high-stakes testing.