Rachel and I know better than to trust the internet. That's why we both tried to make lemon juice batteries this weekend. When they didn't work, we compared notes did some more research and thought we'd gotten the wrinkles ironed out. Time for the big leagues – a lesson with the Herons.
Every student got the materials to make a voltaic battery — a lemon, a galvinized nail and a piece of copper. We talked about how the battery worked and how to connect them to another cell. According to our sources, a typical lemon battery produced .7 volts. The Herons quickly did the math and grouped up so that they would be able to light one of our 1.5 volt bulbs.
Forty minutes later we had not one bulb lit. Rachel and I encouraged groups to identify variables and change them but nothing seemed to be getting us closer. One group even proved that the lemon didn't seem to be able to complete a circuit with a regular battery. Then one group used a team member's tongue as a switch and discovered that, yes, there was a little current flowing. Groups joined together…a little more current. More groups joined but still there wasn't enough to light an LED. Then, with all 20 cells in a series the LED lit…just not brightly enough to be seen outside of my cupped hand. To the kitchen — the darkest place in the school. We hooked up everything again and…wait for it…LIGHT! Each of our lemons produced .075 volts. It reminded me of that mushroom you have to boil eight times before it's not poisonous — how did anyone ever figure this out?
Failure is a huge part of science (and learning). As I explained to one frustrated student, what if Thomas Edison had stopped testing filament materials after 15 minutes? With each failure we learn something that we can apply to the next trial and sometimes, if we're lucky and smart, we eventually find a solution.
The Herons are pretty convinced we just need to use potatoes instead of lemons. I'm skeptical. If anyone has any experience with these kinds of experiments, Rachel and I welcome your advice.
Paul Raveling, Allison's dad, came in today to teach us about his work as an electrician. He took a socket out of the wall and showed the kids how everything is connected. We're still trying to puzzle out three way switches (that let you turn off a light from three different locations) and we're all pretty sure that we need to do conduit pipe bending for our next art project. Paul was a wealth of information and extremely patient with all of our questions.
The Rookery 
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