Concerning the bread, the siege of Leningrad gives a good example of how noble and yet oh so stupid people are: the children were often given two rations, that of their own and that of their parent. When the parent then died the child died shortly afterwards. If the parent had eaten both, there is a much greater probability that at least one of them would survive the siege.

With teachers, there are often "best" teachers for different groups. An exceptionally bright one might be excellent at stretching the brightest, but hopeless at teaching the average / lesser students.

I agree that the best results come from stretching the top to go further, but the ones at the bottom are never going to achieve even what those in the middle could. Surely get the lowest ones to a basic level and spread the rest of the resources amongst the other two groups.