Hi,

My grandson and I are doing the science fair project. He is in 3rd grade. We started to work on this years science project ,today. We covered the scientific method, vocabulary and did a bunch of really cool stuff on "Brain Pop, Jr..  He has his heart set on doing an experiement with a potato making a light go on. The electrolytes in the potato juice will be the substitute for the sulfuric acid that is found in a battery. Pretty neat! My difficulty lies in how to formulate a hypothesis. Since it's not a demonstration, but an experiment, I'm a little bit at a loss, on what kinds of ideas I can suggest to him. I thought of one, using two different kinds of potatoes and picking one as the potato with the most light emitting energy, Do you think that is a good one? I'm hoping one of you all have some more ideas for me. I would like him to pick one on his own, out of many, or maybe he might be inspired to formulate one himself after he sees what other ones are out there.

Here is a potato experiment that is the background for our science project. It does have a hypothesis, but I don't want something that's been done many times over.

http://www.miniscience.com/projects/PotatoElectricity/

Thanks so much for reading my post.

You could do two potatoes, a red and a regular or something along those lines, you could also do which creates a brighter light a potatoe or a lemon or something along those lines as well. I am at a brain freeze moment right now, but am currently working on a lesson unit for electricity so if I run by anything I will let you know!

~Amy

Amy, thanks for writing me. I like your ideas!

We also found a great study that was done in Israel with cooked potatoes instead of raw ones. What they found was the cooked potatoes made the light stay on for weeks. My grandson is interested in doing the cooked potato experiment. We're thinking of comparing the raw potato to the cooked. I don't know if that's too complicated a task. If we do the experiement on the cooked potatoes alone, we could see how long the light would last, but I'm afraid it may last for several weeks. We don't have several weeks. We have approximately three weeks and that doesn't count setting the experiement up and doing the required writing. We could measure how long the light lasts with the cooked potatoes hypothesizing it would last one week. If it lasts longer the hypothesis would be wrong.

Here is a link for this interesting experiment: 

http://www.engadget.com/2010/06/20/yissum-develops-potato-powered-batteries-for-the-developing-worl/#comments

What do you think of my ideas?

What about not only doing cooked vs uncooked, but different types of pototaes or try sweet potatoes as well, along with other produce items. 

What is the problem with having his hypothesis proven wrong?  The objective of most science fairs is to go through the process and learn something from it.  If you do the cooked vs. raw potato experiment with a stated expected time of one week for the cooked potato and it lasts longer, then your son will be able to write that he significantly underestimated the amount of time the cooked potato would continue to keep the light shining.  It would be interesting for him to have the potato to display for the presentation and have a running calendar of just how many days the light has continued to shine past the expected date.  He will have learned from the experiment and I'd be willing to bet that his teacher would love to have the potato stay in the classroom so that the class can extend the experiment by charting the days until the light goes out. 

Hi,

Just want you all to know that my grandson won first prize in the school science fair. for his experiment He got a metal  from the principal and a certificate from the lead science teacher!

The experiment was: can four lemons conduct electricity for 24 hours. The experiment was duplicated. Yes it worked!

I want to thank all of you for your imput. It helped me learn how to present the lesson to my grandson. Not being a teacher and not being allowed to teach the experiement was a challenge, but I pulled it off well, I think. We had some confusing times, some interesting times and a bunch of fun.