We spend 80% of our classroom time on the skills needed

The factory model high school as we now call it was designed in about 1910 or 1920. The idea of that comprehensive high school was to cream off about 5% of the kids for specialized knowledge work. They would go off to college and fill the very small number of jobs that required that kind of thinking. The rest of the kids were supposed to be prepared for the farm, the factory, the mills - for you know, fairly rote kinds of learning. And over time vocational programs were put in place and other kinds of general programs.

We spend 80% of our classroom time on the skills needed for 10% of our jobs | Dangerously Irrelevant