A 'well-structured problem' yields a right answer through the application of an appropriate algorithm. Most textbook problem sets in mathematics, science, engineering, or business feature well-structured problems that have right answers. Examples of well-structured problems (King & Kitchner, 1994, 11) include:

• Converting a unit of measure between its English and metric equivalents,
  
• Solving for X in an algebraic equation, and Calculating the trajectory of a rocket's flight.
  

Contrast this with 'ill-structured problems.' Sometimes called 'ill-defined' problems or a 'messy' problems, an ill-structured problem doesn't yield a particular, certain answer. Ill-structured problems mirror real world problems where data are conflicting or inclusive, where disputants disagree about appropriate assumptions or theories, or where values are in conflict. Disputants may propose different solutions to the problem, each with particular strengths and weaknesses. In approaching an ill-structured problem, the thinker must attend to alternative points of view and create arguments justifying the proposed solution. One responds to a well-structured problem with a right answer but to an ill-structured problem with a claim and a justifying argument. Examples of ill-structured problems (King & Kitchener, 1994, 11) include:

• Determining what really happened at the Hue massacre in Vietnam,
  
• Judging the adequacy of a theoretical proposition,
  
• Predicting how to dispose of nuclear waste safely.