Back-of-the-Envelope Problems.

Abstract : Back-of-the-envelope problems call for approximate calculations of quantities that can be related to information in a person's knowledge but are not solved precisely. They therefore provide an opportunity for study of processes and role of general knowledge in ill-defined problem solving. Subjects with advanced and intermediate knowledge in different domains provided protocols solving back-of-the-envelope problems within and outside their fields of special knowledge. Their protocols were interpreted using a set of distinctions provided by Schoenfeld (1985). A model that simulates important aspects of the observed performance was developed by extending FERMI, a model of general problem-solving methods. An important feature of expert performance was the ability to use domain-specific knowledge in the service of general problem-solving methods. General methods of problem solving were similar across subjects who differed in knowledge. At the same time, expert knowledge probably provided guidance in solutions.