School is almost here. Pretty soon, the familiar yellow buses will be making their way up and down county roads, picking up boys and girls ready and eager (some more than others) for the opportunity to learn.

Which begs the question: Just how much are they learning? For almost as long as there has been school, there have been attempts to gauge just how effective that instruction has been.

In the 19th century, students were tested to determine if they mastered a given subject, and those who didn’t pass were kept back. Only the brightest and hardest working advanced to high school. Teachers, meanwhile, were often required to pass an initial test of general knowledge and interviewed by the school board to ensure they didn’t have any unconventional views or religious beliefs. Once they were hired, that was that. If students failed to learn, it was their own fault.

The system remained pretty much unchanged until the Cold War, when concerns over Soviet dominance in math a...