Potato Clock

For Christmas, my parents had gotten Becca a potato clock. Becca is really into how things work. Using this kit, you can use fruit, vegetables and even soda to make a battery that runs this clock. Andy and the kids put this together (I was studying). But before long, Becca began her own experiments to see how she could alter it and whether or not it would still work. . . "If I put both the copper and zinc into the same potato will it work? What if it is not in the potato? It doesn't work unless I am holding it. Why is that? Is the electricity flowing through me?" Hmm, a future engineer?