Knowledge-lean problems: can be solved by use of instructions for the task and general problem solving skills, e. g. finding parking spot in mall. Knowledge-rich problems: requires specific knowledge or skill to solve the problem, e. g. calculus: 2 kinds of problem, well-defined: problem with a clear-cut solution, can be solved by algorithm. Ill-defined: with multiple possible solutions, can"t solve by algorithm ii. Gestalt psychology and problem solving: gestalt: a whole pattern, a form or a configuration. Difficulties in problem solving: functional fixedness: a. tendency use objects and concepts in problem env in only their usual way, maier, use pliers to swing the strings and tie. Insight thought of deep , useful understanding of the nature of sth, esp a difficult problem. Basics of problem solving: goal: the desire endpoint/ solution of the problem-solving activity. Means end analysis and tower of hanoi: missionary cannibal problem, 3/ 4 disc version: recursive: simpler component embedded in difficult versions.