Systems of synchronization occur throughout the animate and inanimate world. The regular beating of the human heart, the swaying and near co llapse of the Millennium Bridge, the simultaneous flashing of gangs of fireflies in Southeast Asia: these varied phenomena all share the pro perty of spontaneous synchronization. This unit shows how synchronizat ion can be analyzed, studied, and modeled via the mathematics of diffe rential equations, an outgrowth of calculus, and the application of th ese ideas toward understanding the workings of the heart.