We tried to do the potato powered LED, but I could not get it to work for the life of me. I wanted to have a dry run before I got my daughters involved. The initial setup is below, I did not have a galvanized nail to begin with but I was hoping that the bit would work (nope).
After a little trial and error with the below setup I gave up and tried to procure a set of galvanized nails to see if that was the issue. I found some screws that I thought might be galvanized (beats me really). As you can see below this is the initial setup.
1 Nail in both sides of potato's
1 piece of copper in both potato's
Now connect the + side of the LED to the copper from potato 1.
Connect the - side of the LED to the nails from potato 2.
Now take wire and connect the nail from potato 1 to the copper on potato 2.
And from here you should see your light work (or digital clock) or whatever you are trying to power.
Still not good, contacted next door neighbor who had a few galvanized nails I could use and replaced mine.
Still no good. At this point I had to call it a FAIL until I can figure out what went wrong. If anyone can tell me please leave a comment. Also the above picture might not be the one with the galvanized nails in them.