Haha, just to play along, that means that the value added measures are just value captured measures, i.e. It's worse than before. Since a teacher has no effect

Haha, just to play along, that means that the value added measures are just value captured measures, i.e. It's worse than before. Since a teacher has no effect on height, but height has an effect on ability, and height varies just as hard as ability then the variation is attributable to the height and not skill in any sort. I am, as always, quite convinced that teachers aren't that valuable. At least not the kind in public school. What I'd expect from a situation where there is wide variation in teacher ability is for them to form private schools where they extract massive value from the relationship because everyone will want the best tutor for their kids. This can probably happen. But normal teachers aren't it. It's the specialized tutors who get this value. Which means that perhaps all really good teachers become private tutors so you'd expect everyone else to be essentially unexceptional.