The lesson described in this article was developed and taught by a team of mathematics educators and physical therapists, with the shared goal of broadening students' perception of how mathematics concepts are applied in the real world. This lesson gives students authentic experience with the Gait Speed Test as a physical therapist would administer it. In the lesson, sixth- graders generate walking speed data using a fixed distance and measuring time in seconds, convert that to an appropriate unit rate, and interpret that unit rate in the context of health and physical function.