Kids are not so binary.

Plenty of schools have random assignment for students yet teacher A's students vastly outperform teacher B's students. Sure, the best student in B is generally better than the worst student in A but they are still generally behind the best in A.

Do you have any research to back this up? I'm curious.

Yes, I am not sure what part you want support for. But, if this interests you I suggest you do a little research on your own.

(http://www.centerforpubliceducation.org/Main-Menu/Staffingst...)

I have done research and haven't found that "plenty of schools have random assignment for students yet teacher A's students vastly outperform teacher B's students".

I'm very well aware of studies showing that teachers make an impact. That much is obvious. What I'm not aware of is any significant group of schools that regularly use random assignment.

Here is one interesting example: http://www.nber.org/papers/w21407 However, this really comes down to researches not being idiots.

If you mean at the school level, that's a policy choice which is far from universal. However, their are a lot of schools and a meaningful number do random student assignment.

Stand and Deliver was based on a true story.

https://en.wikipedia.org/wiki/Jaime_Escalante