Saturday, November 28, 2009

Experiment 4: Electricity for very small folks

As regular readers know, I am doing science tricks with my 4 and 6-year old at the moment. It's really exhilarating when their little faces light up and they say "Woooooow coooooool!". My biggest problem is finding something that has the requisite wow factor for their age group, when most science education resources are aimed at older kids. This week I was convinced that I'd found The GREATEST Science Trick ever. I was ridiculously excited.

One super awesome idea: Check!
One lemon, some copper wire, a copper nail, a zinc-coated nail, a 1.5 V tiny light bulb: Check!
One battery made from a lemon used to power above-mentioned light bulb: Ready for lift-off!

Here's what to do. Insert a zinc nail into the lemon. Insert a copper nail close by, but make sure it doesn't touch the zinc nail. Attach a copper wire to the zinc nail and another copper wire to the copper nail. Now attach the other end of each copper wire to one of the wires of the light bulb. Stand back, and ..... oh dear...
The lemon didn't supply enough voltage to power the light bulb. Hurrumph. What to do, what to do, what to do....
Wire up several lemons in series! I tried 2, then 3, then 4. Oh dear. That didn't work either.
I know, we'll find something that takes less voltage. Ah ha! The pedometer! (Some people use them for counting steps would you believe! Much better for use in science experiments for small folks I reckon).

You see? See the LCD display ALL LIT UP?! See it working?! (Battery placed nearby so you can tell it's not a rigged shot). It really, truly worked. I was beside myself with glee. "Wooooow coooool" I said, congratulating myself heartily.

There was an eerie silence from the children. My point earlier: most science resources are aimed at older kids. My children don't know how a regular battery works let alone one made from a lemon. They see things lit up from batteries all the time and lighting up the pedometer didn't impress them one bit. As well, all the problem-solving was done by me- I wired up the extra lemons, then knew enough to know we'd need something with a lower voltage drain. They had no investment in this experiment at all, and conseqently no interest. Back to the drawing board then.

Something simpler. Something visual. Something that they can do themselves with tools they use all the time: A simple circuit with a battery and a tiny light. The kids connect the wires to the battery all by themselves using cellotape. (Approximate cost: $3.00 for the battery and $0.86 for the little light from Dick Smith Electronics). They soon worked out that both wires must be attached (it must be a complete circuit) and that the wires must be touching the metal itself. That's pretty good problem solving and they did that all by themselves.

And this is the reaction I was looking for:

The light they made all by themselves was carried around all day, taped to a hat to make a head light, pushed into tiny spaces to see what they could see in there, and was frequently connected and disconnected. That's what I call an experimental success.

(P.S. Even though my very little children weren't interested in the lemon battery, it would be great for older kids. I have loads of copper wire, copper nails, and zinc coated nails leftover and I will gift them to NZ readers until I run out. Email me at if you would like me to post some to you, along with the wiring layout for making a lemon battery. NZ readers only, sorry, postage costs get a wee bit prohibitive to anywhere else.)

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  1. The tanned cat hide my physics lecturer used to create static electricity always impressed (and horrified) me. I am in no way suggesting you endanger the family pet, merely that I was impressed. I'm pleased to see the light bulb finally went in both senses.

  2. It really makes me giggle to picture you getting all wrapped up in your experiment and the children looking at you like you've lost it a bit. This is great! Bravo, Miss Smith!

  3. You should do the diet coke and mentos fountain, they are pretty spectacular! It's a similar reaction to the egg on you did earlier only it creates thousands more bubbles which shoot up in a fountain

  4. Love love love these posts! Vic.

  5. I don't know why but the thought of 4 lemons all wired together is so comical, not to mention the kids carrying the light around all day. It's lovely to be into Dec: small note there are 2 birthdays this month that I know of...