Tuesday 4 November 2014


A couple of months ago I was dropping Naomi off at Nursery, and her key worker came up to me. She said "Naomi tells me that she is very proud that her Mummy and Daddy are scientists, and as we are looking at science just now, I wondered if you would like to come and do a presentation for us?" Well, I suppose I am a computer scientist, Jay did chemistry at uni, and we do take a general interest in such things...

Being the extrovert that I am*, naturally I leapt at the chance. A couple of days later, Jay and I agreed that we could do something, probably mostly chemistry based. We settled on a date (21 October - after the tattie holidays but hopefully plenty of time before D-Day) and indicated that we'd do it. This would be for the whole nursery, so around 30 3-4 years olds.
*this may be sarcastic

We had a lot of fun trying out different experiments we could do. Try going for "kids experiments" in YouTube for some ideas! Eventually we settled on a set of four things that we could do. Here's a bit of a summary - it's all stuff using household things so you could replicate them quite easily. In the end we were quite pleased that we held the attention of a whole nursery for nearly 20 minutes. Result!

We explained who were were, that some people like science as a job and some people like it just for fun. It's all about understanding how things work, some of which you can see and some you can't. We then confused the children by telling them that I'm a "different kind of doctor". Following the obligatory disclaimer about not just doing experiments with any old stuff you find in the house, we got on with the experiments. As we always do with Naomi, we tried to explain what was going on, and were quite impressed with how much the children took in.

Iodine clock

This is explained in detail here. This one uses the most exotic chemicals of the lot, but all available from the pharmacist quite cheaply: iodine, vitamin C (we used soluble tablets), hydrogen peroxide (which can be used as a mouthwash), and corn starch (cornflour). The idea here is that you mix these together in two stages. The first one changes the iodine from brown to colourless instantly. The second mixing sets off two reactions, one of which you can't see but stops the other reaction happening straight away. After a while, the final reaction can get going and the mixture changes to blue-black quite dramatically. A video of a less-impressive version from one of our practice experiments is below. On the day, it worked perfectly: the delayed colour change kicked in after about 40s (the practices had it at anywhere between 30s and 5 minutes as I was being quite imprecise with measurements). This allowed just enough time to explain it and for some people to get bored and look away, only to be drawn back by the others going "ooooh". Great!

This starts straight after the mixing has happened. The first two minutes of this are pretty boring. Skip to near the end to see the colour change if you like!

House drawing

A node towards my work, we explained how computer programs work, I gave instructions to Jay on how to draw a house, and we worked it so that I just gave shapes rather than where to put them, and Jay ended up with a muddle rather than the nice house we'd prepared earlier. The idea was to show that computers are only as clever as the instructions that they're given, which must be right.

Vinegar battery

Okay, so not everyone has some LEDs lying around, but in this one we made a battery and lit up and LED with it. The same principle as the more well-known lemon battery (and most single-use batteries), this uses the effect that two different metals in an acid create a voltage between them. See here for a little more detail. Take some plastic cups, fill with water, vinegar and a little salt, and put in a galvanised nail and a piece of copper (I took some from a piece of twin and earth). Three of these in series is enough to light up a red LED, although not very visibly in a bright nursery!

Hot / cold water density
Demonstration that hot water is less dense than cold, so it floats, explained here. Take some tap-hot water and add red food colouring, and cold water with blue food colouring. Put into separate glasses (filled right up to the brim), put a plastic panel on top of the hot one (we used a cutout from a takeaway tub lid). Carefully tip the hot one upside down, place on top of the cold, and remove the panel. The hot and cold stay separate rather than mixing up, because the hot is less dense and floats on top of the cold. (time didn't allow this for us, but you can do it the other way round to show that the hot and cold swap around if the hot starts on the bottom, mixing up and turning purple in the process). Naomi remembered this one about a week later when we were talking about something else - I think it was about how balloons float!

We then finished with some general questions from the children:
  • Where can you buy a magic wand?
  • Why is the sky red at night?
  • How do planes stay in sky?
I think we did a reasonable job with these too :)

Obligatory photos follow. Obviously we can't show ones with non-Brownlee children in, so you'll just need to trust us when we say that they were captivated!

Naomi points to the "Science is Awesome" sign in the nursery

"You mix this in here, then this in there"

The battery

Adding some vinegar

Mixing up the iodine clock

Good explanations are always accompanied by gesticulations

Explanations were a little delayed in places because Miriam joined us and wanted to help. Mummy to the rescue!

The house that needed drawn
Trying to draw the house

Naomi was quite concerned that her Mummy couldn't draw the house, so she showed her how to do it.

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