The box in the upper right is a battery, with two wires coming out (black and red). The two wires are connected to different parts of a ball of green putty which has tiny LED light bulbs stuck in it. The wires from the battery are NOT connected to the wires of the LED lights, yet the lights are still lit up. Why? The putty is acting as a conductor of electricity. The current supplied by the battery travels through the putty to the wires attached to the LED lights. As long as there are no breaks in the connection anywhere, the LED lights will light up. Super cool!
You can do something similar with potatoes, lemons, and other household objects. I'm adding this to the list of science experiments to test out this summer with my kids.