The main purpose of writing equations in math is to generalize observed patterns and make predictions. For students to make predictions using their generated equations, they must understand the variables involved. Allowing students to write what each variable represents aids students in predicting various circumstances. For example, in the Barbie Bungee project, students make equations in which the independent (x) variable represents the number of rubber bands, and the dependent (y) variable represents the total length of the fall. Once the variables are identified, we substitute known values to solve for unknown values. In the Barbie project, we can substitute known rubber band amounts to find the length of a fall. We can substitute known falling distances to solve for the number of rubber bands needed.
