re: What exactly was the "No Child Left Behind" Act?

It was written by Ted Kennedy (D), and passed by Bush. Sure seems to have worked, considering how many Chicago schools alone don't have a single student proficient in math at grade level.

This is a decently evenhanded review, but notice how many waivers were passed.

Teachers (unions, at least) hated it because it involved measuring teacher performance (which was later watered down to be meaningless.)

I think was Reagan that mentioned that the Department of Education had never taught a single student, so why did it even exist with so much funding?

You're not missing much. They do write lengthy academic papers about what worked and what didn't, which nobody will read, but FedGov probably funded those after actions too.