It's too bad every student who is struggling in a subject can't get more personal attention and instruction, but clearly the only cost effective way to teach groups of people is to clump them by age alone and move them through a system of narrowly defined academic classes driven by broadly defined 'subjects.' It's such a shame that a person's age and peer group are the only things that really define their skills and interests. Wouldn't it be great if we could just trade the whole 12 year age-based, fixed growth, large class structure for something like, oh I don't know, individualized certifications in specific skills, interests, or subjects?