Children of the same age are ready and able to learn the same subjects at the same level. Nutrition doesn't impact learning. Spiritual and moral principles must not be taught in a publicly endorsed system. Anyone who has taught in public school quickly realizes how little learning is accomplished and how much demoralization the children and teachers take on.
Teachers sometimes feel they are at fault, children blame themselves, parents blame both.
Actually it is the design which is at fault. It cannot be repaired with simple quick fixes. We believe that it cannot be repaired at all. Start something new and better. Let the old system die a natural death.