I'm curious about what blue collar trade requires the most academic knowledge to perform in a competent manner. I'm not asking what blue collar trade requires the most knowledge or skill to perform competently. I'm asking about academic knowledge only. Both HVAC technicians and electricians have to be capable at using arithmetic and algebra to perform competently. For instance, frequently HVAC technicians and electricians deal with three traits on an electrical system: Voltage (V), current (I), and power (P). Power= Voltage X Current -- Often, HVAC technicians and electricians will know two of the three variable, and then the HVAC technicians and electricians will have to solve for the third variable by isolating it and dividing (or multiplying) both sides by the same thing. This is a linear equation type of algebraic equation. This is what people learn in Algebra 1. Automobile mechanics need to know the physics principle that liquids cannot be compressed. Understanding this principle of physics is vital to understanding hydraulic brake systems. I believe the principle is called something like Pascal's Law. I know other blue collar trades use academic knowledge as well. By academic knowledge, I mean strictly academic subjects such as English, mathematics, and science as opposed to technical knowledge. Possible blue collar trades as answers to the question of this thread include but are not limited to the following: automobile mechanic, plumber, HVAC technician, aircraft mechanic, and machinist. In what blue collar trade does a person have to know the most academic knowledge to perform the work of that blue collar trade in a competent manner? Please elaborate on why you think that the blue collar trade that you mention requires the most academic knowledge.