When people fall and experience problems of balance, physical therapists (PTs) often prescribe home balance exercises involving repetitive head movements. Currently, patients' compliance and performance of these home exercises are invisible to PTs, who need the data to make informed decisions for treatment adjustments. We present an easy-to-use tool that monitors patients' home balance exercises and provides PTs with accurate, quantitative patient data. The tool, Head Coach, is a wearable device implemented in an iPod, fitted in a pocket on a baseball cap, and worn by patients while doing their exercises. We tested the reliability of the system using a magnetic field tracking device (Polhemus) as the gold standard. The test showed that the iPod can be used to accurately track home balance exercises.