You will need 2 potatoes, 2 pennies, 2 galvanized nails, 3 wires with connectors and a calculator. Take the pennies and stick them in each potato. Then place one nail in each potato as well. Next take one wire and connect it to the nail on one potato and then the other side to the penny on the other potato. Then take another wire and connect it from the penny of one potato to the battery terminal on the back of the empty calculator. Do this with the third wire as well. Turn the calculator over and it should be working.