How do you measure return? We already have data to tell us how to teach for the best return. Look back to when we were less dissatisfied in the results in our educational system, use that method again. Dumbing down the system so that every one is accepted, dumbs down the country as a whole. The education system that was turning out rocket scientists back in the 50's and 60's seemed to work the best IMHO.
No child left behind is ridiculous. Not all dumb kids can be made smarter but all smart kids can be made to be dumber.