From PVreeland:

• I just wanted to share a picture from the ice cube tray battery lab. I used lemon juice as the electrolyte and it was neat to show students the evidence of a chemical reaction that appears on the zinc electrode.
• The image on the left is how the screw looked at the start of the lab (I pointed out to the kids that these screws have been in the shop for over a decade and are still shiny)
• The middle and right images show the screw after being part of a battery for 20 minutes. You can even see how the top portion of the screw not submerged in the electrolyte is still shiny.

• Galvanic/Voltaic Cells Virtual Lab