A discussion is presented concerning variables associated with children's representation of certain addition and subtraction problems. Problem components are classified as physical, pictorial, sensual, verbal-spoken, verbal-written, symbolic, or internal. Problems are discussed as abstract (symbolic) or nonsymbolic. Three problem components are identified and discussed: (1) measurable entities, (2) contextual relationships or actions on entities, and (3) characteristics of the missing number. The second component is further broken down into joining, separating, equalizing, part-part-whole, and comparison. Problem structure is also discussed. (MK)