Mathematical proof is an expression of deductive reasoning (drawing conclusions from previous assertions). However, it is often inductive reasoning (conclusions drawn on the basis of examples) that helps learners form their deductive arguments, or proof. In addition, not all inductive arguments generate more formal arguments. This article draws a distinction between inductive reasoning, which successfully lays the foundation for more formal arguments, and other inductive reasoning, which does not. The strategy of identifying inductive arguments that prompt formal arguments is an important skill for both middle school teachers and teachers of prospective middle school teachers. This article was triggered by the Morris finding that many junior and senior prospective K-8 teachers in her study "did not appear to understand the relationships among mathematical proof, explaining why, and inductive arguments." (Contains 4 figures.)