How to Make Hydrogen
This is a fun experiment for kids, and needs only minimal parental supervision, according to how far they take their curiosity.
What is hydrogen and where to you get it? Hydrogen is a gas, and the most common place it is found, is in water. The chemical formula for water is H2O, meaning two parts of hydrogen plus one part oxygen, makes water. So the most logical place to find hydrogen, is in water!
Take a small glass bowl that will hold two cups of water. A soup bowl is good because there is some depth to it, which you'll need to get the most visual fun out of the experiment. Take a couple of pieces of copper wire, or in a pinch, you can even use paper clips, and fasten one to each of the terminals on a 9V battery. Stick both ends in the water and watch what happens.
You'll get a stream off bubbles off each wire, but one will produce more and faster, than the other. That's your hydrogen. What you are doing, is sending electrons down into the water, which remove the proton from a water molecule and the two bind together, forming a hydrogen atom.
You can speed up the bubble production by adding a teaspoon of salt to the water, which increases productivity, and also by hooking more batteries together, by plugging one into the other. The showman's trick, is to strike a match over the bubbles and demonstrate the difference in the gas that is released from them. Over the oxygen it merely burns, and over the hydrogen, you get a puff of flame.