“Everyone has the brainpower to follow the stock market. If you made it through fifth-grade math, you can do it.”
--Peter Lynch

For Peter Lynch, a common sense understanding of a business goes much further than any textbook financial theory. In his writings, he attributes much of his success to understanding non-quantifiable aspects of a business. Things like customer satisfaction, expansion plans, and product strategy are much more important than forecasting the next quarter's cash flow. Lynch's approach is a roadmap for anyone seeking to beat the market, which he doesn't even think is too difficult. The only thing I'd add is that understanding exponential growth can be helpful, and that is usually taught after 5th grade.