As students develop algebraic reasoning in grades 5 to 9, they learn to recognize patterns and understand expressions, equations, and variables. Linear functions are a focus in eighth-grade mathematics, and by algebra 1, students must make sense of functions that are not linear. This article describes how students worked through a classroom task that was designed to introduce quadratic functions. According to the Common Core's Standards for Mathematical Practice, students demonstrate mathematical modeling when they apply what they know and are comfortable making assumptions and decisions to solve complex authentic situations. Steen (2001, p. 2) argued that to thrive in the modern world, citizens must "see the benefits (and risks) of thinking quantitatively about commonplace issues, and to approach complex problems with confidence in the value of careful reasoning." The classroom example described shows that students identified important quantities in practical situations and chose appropriate representations, such as diagrams, tables, graphs, and formulas, to communicate their understanding. This proved to be a powerful illustration of how to "Model with mathematics" (CCSSI 2010, p. 7). Selling muffins introduced students to quadratic functions. Communicating with tables, graphs, and formulas helped solidify their understanding.