This document discusses problem validation, which is an important part of the entrepreneurial process. It introduces the four steps of problem validation: 1) getting buy-in that problems, not products, are the focus, 2) hypothesizing what problems exist, 3) discovery through customer interviews to validate problems, and 4) confirmation by testing a minimum viable product or solution and seeing if customers will pay or "currency test". It provides examples and exercises to help teach these concepts in an entrepreneurship class.