Research has shown that students should be given the opportunity to explore mathematical concepts by building on their knowledge and focusing on mathematical reasoning. When students represent ideas, make conjectures, collaborate with others, and give explanations and arguments, they are using mathematical reasoning (NCTM 2000). Certain teaching practices can support students' mathematical reasoning. The topic highlighted in this article--integers--was selected because it poses unique challenges. A person's financial net worth provided the context for these activities. The focus was on helping students understand how assets and debts were quantitatively composed in a net worth statement and how integer operations worked in this context. (Contains 4 figures.)