As they do their work, physical therapists apply mathematical ideas. Teachers can use some of those applications to inspire students' discovery of new concepts. In particular, the joints of the human body provide a way to represent angles that is accessible to all students and can be understood in the elementary grades. Used with fourth graders, the lesson described in this article gives students hands-on experience with a real-world tool used by physical therapists. Students use the tool, a goniometer, in the same way a professional would: to measure joint range of motion and connect that motion to an understanding of how an angle is formed and measured. Lessons such as the one described in this article that connect to something novel or something that piques students' curiosities will influence their view of the discipline and can shape their mathematical confidence.