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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Sunday, November 22, 2009

First aid

I've got lots of little half-finished projects lying around at the moment.
Case in point: A small first aid kit that's been waiting for me to sew it up. I made it from a felted woollen jersey that I bought from the Red Cross Shop for $3.00, with some ticking lining. Very appropriate, don't you think? An item from the Red Cross Shop being made into a red first aid kit, with a cross?

(Okay, I'm whispering this to you now. You know the term "phallic symbol"? Photos of little purses like this with the zip undone, well, they make me laugh because they seem to me to be the female equivalent of a "phallic symbol". Stifled giggles~ fnur fnur).

If you don't mind, I'd like to quickly gloat about how neat the zip is. It's become a point of pride because there have been periods of my life in which my zips were not neat at all.

I followed a tutorial for the first wee purse I made like this, and it was a piece of cake. For the life of me I can't remember which tutorial I followed, but it was similar to this one.

After sewing this I realized I should have used a walking foot to stop the seams from flaring- there's quite a bit of stretchiness in felted wool, and it's pretty bulky. As well, I ran a couple of lines of hand stitching around the inner edge to hold the seam flat and stop it getting caught in the zip. The little cross is a piece of felt, handsewn on at the end with a simple edgestitch. Easy.

What dinky little handmade things are you making at the moment?

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Wednesday, November 18, 2009

Experiment 3. What does science taste like?

Last time the littlies and I did "science tricks" together we noticed the gas (carbon dioxide) given off when you mix an acid (vinegar) and a base (calcium carbonate/sodium bicarbonate). The kids were dead keen to do the baking soda/vinegar trick again. "Sure" I said "But shall we see what this reaction tastes like? We could make bubbles on our tongues!"

"...Okay..." they replied, in timid voices. I trotted off to the cupboard and brought back the ingredients for sherbet.

Mix together: 1/2 t citric acid, 1/4 t baking soda, and 3 t icing sugar. Grind them up in a mortar and pestle if you have one. Make sure they stay nice and dry.

Now put a little in a glass and get a straw. Suck a little up onto your tongue and feel it fizzing as the acid (citric acid) reacts with the base (baking soda). This is the taste of a real-life chemical reaction on your tongue. The acid will taste sour and tangy, and the sugar will be nice and sweet. There's also a rather scintillating cold feeling- that's because this reaction is endothermic (it absorbs heat to break the chemical bonds).

Baking soda, citric acid, icing sugar: A few cents. Sylvie's expression: Priceless.

Harry thought that adding water might make it into a fizzy drink. We tried it out. It fizzed alright, but the bubbles were gone by the time he drank it. (This showed him that the reaction is instantaneous).

Sylvie thought that the flavour could be improved. We talked about other things we could put in to make a different flavour: powdered fruit drink, jelly crystals, different types of sugar. Whatever flavour you choose, it must be dry, because the reaction happens as soon as you add water.

My old life is creeping into my craft blog, and it feels strange. I think I might have to call these posts "science craft" to avoid freaking myself out.
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Thursday, November 12, 2009

Never, never, never

I love pieces of advice that start with "Never". I always have.
When I was a teenager I worked in a retirement home.
A lady there used to say: "Never marry a man you meet in church".
Here's one from my friend Kelvin: "Never refuse a cup of tea".
From our builder: "Never ask a plumber to cut wood".
My Dad used to say: "Never explain, never apologise, and never do anything for anyone". This was rather funny because he frequently explained, apologised when necessary, and constantly did things for everybody.
From Simon: "Never eat something that's larger than your head".
And from Me: "Never miss an opportunity to show off your latest robot".

Have you got any "Never" advice? Please share.

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Sunday, November 8, 2009

This is a robot hijack

Sometimes when I'm making a robot a small person appears at my side saying "Can that be my robot Mum? Please? Pretty please with sugar on the top and hundreds and thousands and chocolate chips?". Well I'm a soft touch for any request sprinkled with chocolate chips so I almost always say yes.
The small folks are so hilarious in how they want their special robot decorated. It's always the biggest, craziest buttons from my button box, and they're not especially into dials and screens or other controls. Just big vintage buttons that make rather eccentric control panels and very spooky eyes, once you sew them on.

I'm perfectly happy to sacrifice the odd robot to their quirky requests, especially if it means they write great stories about them at school like this:

A robot and a person falling in love...sigh, what a sweet idea. I can feel a puppet show coming on starring Spooky Robot and Barbie. She's got to be good for something.
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Tuesday, November 3, 2009

Experiment 2. An acid plus a base

Science for preschoolers and small children, (cont). Here's an easy one that you can do in 3 min. Baking soda plus vinegar gives loads and loads of fizzy bubbles.

This "science trick" loosely demonstrates that sometimes, mixing two substances together gives a reaction. If you like, you can start off with some other mixtures that don't give a reaction, just to hammer the point.
For example:
If you mix sand and water nothing happens.
If you mix water and sugar the sugar dissolves, but that's all.
If you mix baking soda and vinegar, you get loads of fizzy bubbles, wow!
We played around with this for about 20 minutes, working out how much we baking soda we could put in the glass without the bubbles fizzing over. In the end we came up with 1 t baking soda and 1/4 c white vinegar.
The chemical reaction here, in case you're interested, is that mixing an acid with a base gives a salt plus water. A byproduct of this reaction is the production of carbon dioxide, which is given off by the baking soda as the acids rip off their hydroxyl group. My kids don't care about that part, and it would kill the fun if I started going on about that anyway. This science trick is all about noticing a reaction occurring.
Okay, that was fun. But do you want to see it in slow motion? Lets use vinegar to react with a different base: an egg shell. The egg shell is made of an alkaline calcium compound. If we drop an egg into some vinegar and leave it a while, the vinegar will dissolve that shell clean off, leaving a funny wobbly shell-less egg.
Here goes: Get a load of this! As soon as you cover the egg in vinegar there are zillions of little bubbles forming. That's the carbon dioxide again, being produced as the acid reacts with the base. All those bubbles make the egg float. It's like watching a lava lamp as it bobs to the top of the jar. The shell starts to dissolve off in layers, see?
After a day, we washed off the last bits of the shell under the tap. It was soft and chalky and washed off with no problem at all. We all held the wobbly shell-less egg.
If you think the kids look a little underwhelmed it's because they are. "That's kind of disgusting Mum", said Harry.
Well, yes it is I guess. Perhaps this is also a lesson in how we do not like it when people use chemicals to mess with our food.
Me: "Yes it's funny to see an egg without a shell. But isn't it cool that the vinegar dissolved the shell off?
Harry: "Um...well I just don't know."
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