Prior to the experiment, set the stage and get children excited about the science project. Discuss with children some of the common ways that electricity is generated: coal, magnets, wind and water. Ask children if they can think of an alternative way to produce electricity. Present children with a potato and ask them to predict whether or not they believe the potato will be able to generate electricity.
In order to conduct this experiment, you'll need to gather a collection of supplies. The supplies consist of two potatoes (any type will do), two galvanized nails, two pieces of heavy copper wire and three alligator clips. You'll also need a source that can be used to illustrate that the potatoes can conduct electricity, a low-voltage, battery-operated LED clock.
Get all of the components on your supply list ready for the experiment. Insert one nail and one piece of copper wire into each of the potatoes; make sure that the nails and the wires are placed far away from one another. Remove the battery from the clock and use alligator clips to attach the copper wire from one potato to the positive terminal and the nail in the other potato to the negative terminal in the battery compartment of the clock. Connect the nail in the first potato to the copper wire in the other potato with the third alligator clip.
Once all of the components are set into place and have been linked to the clock, the LED display on the clock should begin to blink. This is possible because the zinc in the nails responds to the copper in the wires and the potato acts as a barrier between the two, enabling them to work together to generate electricity and operate the clock. Potatoes aren't the only foods that can be used to conduct electricity, lemons and oranges can also be used in this experiment.