This chapter explores how simple circuits constructed from switches, batteries, lightbulbs, and wires can carry out logical operations.

In these circuits, toggle the state of the switches with either mouse clicks or finger taps. The color red indicates that electricity is flowing through the circuit.

A pair of switches can be wired in series to implement the logical operation AND.

Wired in parallel, the pair of switches implement the logical operation OR.

More complex logical expressions can be realized by combinations of switches in series and parallel, such as this circuit to determine if a particular kitten satisfies a set of criteria: