Problem is difficult (obstacle between present state and goal), solution is not immediately obvious. well-defined: usually have a correct answer, procedures that will lead to a solution. Ill-defined: does not have one correct answer, path to solution is unclear. Mental set preconceived notion about how to approach a problem, determined by past experience and knowledge. me n t al s e t influ e n c e d p r o bl e m s olvin g. Modern research on problem solving: the information-processing approach. Illu s t r a t e s m e a n s-e n d a n alysi s. Pro bl e m s olvi n g is a p plic a bl e t o r e al life. Conditions after each step is made toward solving a problem. Actions that take the problem from one state to another. All possible states that could occur when solving a problem.