In town I live in High school has auto shop and also have "Building Trades class". I guess its the school that buys home lots and the Building Trades teacher and the students build a house from ground up. They sell it and put profit in the pot so they can buy more lots to build again. The teacher is a carpenter by trade and they do what they can do, but they hire qualified tradesman, concrete, plumbing, electric etc. to work on the house.
The qualified tradesman do their work and let students help and teach kids a little about their trade. I am a plumber and worked for a contractor that was a part of this.