Preparing the metal strips
Use a small piece of sand paper to clean the metal until the
surface is clean and shiny. Wipe the metal with a laboratory
tissue to remove any dirt or small metal slivers clinging to the
surface. Finally, firmly clamp the metal that will be reduced
into the alligator clip on the red lead and the metal that will
be oxidized to the alligator clip on the black lead.
If you are unsure which metal will be oxidized and which will
be reduced, simply clamp one of the metals into each of the alligator
clips. Be sure to record the color of the alligator clip into which
each metal was clamped.