Sometimes I wonder if "school comparisons" are just nonsense. It's usually clear that they are comparisons of students, not of the quality of instruction, except perhaps to the degree that they influence each other. There is a certain percentage of kids out the there that are auto-didacts. They are going to learn the stuff just by being given a reasonable textbook and some time to practice. They make schools that have more kids that can do this look better than they are, and vice versa. Maybe that's what we should be teaching, teach people how to learn on their own.