In this activity 50-socket strands of incandescent holiday lights are cut to produce 2-socket strands and 6-socket strands. One of the incandescent bulbs can be replaced with a light-emitting diode (LED). Typical LED circuits contain a resistor to limit current flow; in these circuits that function is performed by the remaining incandescent bulb(s). The diode nature of LEDs is demonstrated, as well as the energy associated with different wavelengths of light. The activity illustrates the structure and properties of matter, the interactions of energy and matter, the relationship of energy and color, and the contributions of chemistry to high-tech materials.