This document discusses circuits and circuit elements. It begins by defining a circuit as being made up of a power supply, connecting wires, and circuit elements that allow current to flow from the power source through the elements and back to the power source. Common circuit symbols like batteries, bulbs, switches, resistors, voltmeters, and ammeters are presented. The two main types of circuits - series and parallel - are described. Key formulas for calculating resistance, current, and potential difference in circuits are provided. An analogy between electricity in circuits and flowing water is described. Worksheets for activities are referenced at the end.