The problem in education is that it's very hard to separate what works and what doesn't because there are too many subjective factors. If Tommy diligently prac

The problem in education is that it's very hard to separate what works and what doesn't because there are too many subjective factors. If Tommy diligently practices math every day and does all his homework, but gets worse test scores than lazy Billy, it's impossible to know whether he is studying in a counterproductive manner, has poor test-taking technique, or is just less able than Billy. If the inverse is true, intuition and a desperate desire for justice tell us that Tommy's hard work is what made his performance better (and possibly, that he works harder because he's more intelligent).