Computers consist of electronic circuits, which use electricity to receive, transfer, process and display information. This unit develops the basic principles of circuit operation, beginning with a coin battery and light emitting diode (LED). Students are challenged to make the LED light up, and then explore the operation of this simple circuit using a circulating penguin toy as a model for explaining concepts of source, load, conductor, insulator, voltage and current. They explore which combinations of LEDs will or will not light up together, and test a variety of materials to determine which are insulators and which are conductors. Following a “Switch Hunt” for switches in the environment, they create their own switches and add them to circuits. They then explore the operation of this simple circuit using a circulating penguin toy as a model for explaining concepts of source, load, conductor, insulator, voltage and current. Finally, they create “electric puppets” whose two eyes light up when a hidden switch is closed.