CAUTION! Do not breathe the fumes or place your face by the water. Don't drink the water either. Just use common sense of observing and taking notes from a distance for your safety!
Pour water into the glass. Place a little salt or baking soda in the water and stir. Place both pencils in the water in a vertical manner. Attach the ends of the alligator clips onto the tops of the pencils. Attach the other ends of the alligator clips onto the 9 volt battery terminals.
July 23rd 2008, I built and filmed these 4 step by step videos for a home made device that works!
This is a basic experiment that you should be able to do safely at home. But, be very careful. If in doubt ask your science teacher or parent if you are not sure about doing this safely. Safety is the utmost importance.