The When and Why of Using Proportions

Ratio and proportion are fundamental concepts, and yet a significant number of students are not able to solve problems that involve proportional reasoning. Here, Heinz and Sterba-Boatwright highlight some of the fundamental components of the understanding of ratio and proportion and explore ways in which they can help their students develop this understanding. They conclude that their students may be successful in solving a variety of problems involving ratio and proportion, yet their understanding of ratio and proportion may be incomplete. Students may be able to identify a ratio in a problem, but they may not know that the ratio can be the basis for writing a proportion or that it gives them a slope that can be used to write an equation of the form y=mx.