Fostering algebraic thinking is an important goal for middle-grades mathematics teachers. Developing mathematical reasoning requires that teachers cultivate students' habits of mind. Teachers develop students' understanding of algebra by engaging them in tasks that involve modeling and representation. This study was designed to investigate how students' ability to reason algebraically through modeling and representation was affected when they were asked to create word problems involving their personal interests. Using a case-study method described by Creswell (2007), the author interviewed students to gain in-depth knowledge into how this activity affected their understanding of how equations and inequalities can be used to model and represent real-world phenomena. The goal was to see how an open-ended assignment that allowed students to make choices affected their conceptual understanding of algebraic representations. (Contains 1 figure and 1 table.)