"Electricity is the flow of electrons" is an important developmental concept for children to learn. The ball electroscope was invented in 1754 by John Canton. Today, a children’s version can be found at www.nuclearconnect.org/in-the-classroom/for-teachers/making-atoms-visible-electroscope. (image from this source) This is a device that a 6-years can make, have fun with, and learn about electrons. A Styrofoam plate is taped to a table and rubbed with wool or polyester. The electroscope is put on top of the Styrofoam plate. The aluminum ball repels from the aluminum plate indicating that they both have excess electrons. If the aluminum plate is touched, then the excess electrons will flow away through the person and the ball will drop to show the loss. This experiment also introduces the concept of conductor and insulator. Touching the Styrofoam cup has no effect because it is a insulator while touching the aluminum discharges because it is a conductor. All electrical circuits depend upon conductors to channel the flow of electricity.