Materials:
tupperware-like container, 1/4" rubber grommets (2) (get from a hardware store), pencils, alligator clipped jumper leads (2), small test tubes, 1 M NaHCO3, or 3 M H2SO4 solution
Drill 2, 3/8" holes on opposite sides of the bottom of the container
Insert the grommets in the holes. This will be a tight fit!
Sharpen both ends of a pencil (golf pencils work well).
Insert the pencils in the grommets until about 1 cm sticks into the container.
Attach the other end of the pencils to the power suppy.
Fill the container with the electrolyte solution. Bill Nye says the 1 M NaHCO3 solution works. I get better results with the 3 M H2SO4 solution.
Fill 2 very small test tubes with water.
Invert of the ends or the pencils to catch the gases evolved.
Test the gases with glowing and burning splints.