Since we're still having fun with our home made batteries and circuits, we decided to expand our circuit by adding a switch. First, we took apart an old flashlight and used the switch in our circuit.
Then we decided to make our own switches.
Here is a Push Button switch made from cardstock and foil.
We glued 2 pieces of foil on the inside of a piece of folded cardstock. Then we cut two short wires, exposed the copper wiring inside and placed them under each piece of aluminum foil. If you don't have wire, you can just extend the 2 pieces of aluminum foil and roll it to create a little tail for the alligator clips to attach to.
Next, we made a sliding switch using 2 nails, 1 paperclip, and a wooden block.