“Researchers have separated addition and subtraction problem into categories based on the kind of relationships involved.   These include Join, Separate, Part- Part-Whole and Compare problems.   A different problem results depending on which of the three quantities in the structure is unknown.” (Van de Walle, 2001).   In this module we will briefly explore the four types of addition and subtraction problems.    It is necessary for the teacher to understand and identify the problem types, so that a student can be exposed to all four types during instruction.