A general topic is divided into smaller, interrelated pieces (e.g., a puzzle is divided into pieces).  Each member of a team is assigned to read and become an expert on a different topic.  After each person has become an expert on their piece of the puzzle, they teach the other team members about that puzzle piece.  Finally, after each person has finished teaching, the puzzle has been reassembled, and everyone on the team knows something important about every piece of the puzzle.

-University of Michigan CTL