Write an article based on this "Touch the 9-volt battery terminals to the battery clip for one to two seconds. Remove the battery. Read the output on the voltmeter."
The battery is needed only to send an initial current through the wire to cause the hydrogen in the water molecules touching the electrodes to separate from the oxygen, forming bubbles around the electrodes. This process is called electrolysis.  Notice the bubbles forming around each electrode. One electrode has bubbles of hydrogen, while the other electrode has oxygen bubbles. The battery source does not need to be completely attached the clip, just touched to the battery terminals to begin the reaction. The battery is only needed to initiate the reaction. The separated hydrogen and oxygen will recombine into water, releasing the energy originally used to split them as electricity. The platinum in the electrode coils serves as a catalyst to speed the recombination of the hydrogen and oxygen into water molecules. Initially, the output may be as great as two volts, but will decline as the hydrogen bubbles dissipate, quickly at first and then gradually as the last of the bubbles pop.  A light bulb or LED may appear bright initially, but will quickly dim and then gradually fade away.