The author of this article is the founder of knewton, and educational software company for k-12. Their software optimizes questions and educational material for

The author of this article is the founder of knewton, and educational software company for k-12. Their software optimizes questions and educational material for student based on measuring how fat the students are answering questions, in what types of questions they are wrong, etc. They are deployed in some schools , and they show a big improvement for student results. So i'm not so sure measuring is "functionally impossible"