Singing rods are long aluminum rods that produce sound when stroked with rosined fingers. Holding the rod at its midpoint and rubbing along its length causes it to vibrate in its fundamental mode or harmonics. The rod emits a clear tone, and pressing the end of the rod to a surface like a Styrofoam cup can amplify the sound. This demonstration illustrates the principles of longitudinal standing waves, resonance, and the harmonic series.