Within the cognitive tradition, the set of thinking processes or actions involved in the solving of a problem. Problems may be routine or novel. Routine problem solving involves moving from a given state to a goal state based on a solution plan primed from similar past experiences. In contrast, novel problem solving entails the problem solver moving from a given state to a goal state by inventing the solution procedure. (Source: Seel 2012). Increasingly referred to as a key competence/competency and 21st century skill.