## Electricity and Heat

Our final classes in this term exploring The Physical World.

We switched the activities around because I was waiting for a delivery of electrical components but both groups covered basically the same stuff.

# Heat

The children love playing the ‘solid-liquid-gas’ game where they pretend to be particles that move around more depending on how much they are heated up. We have done this since we first covered materials science and they often ask to play the game even if it does not relate to our current topic! Each time I introduce the game, I explain how they have to stand together in a fixed position to be a solid, start to jiggle around as the solid heats up, move around a bit more but stay near to each other for liquids, and run around in straight lines as gas particles. It translates the concepts into physical activity, and is wonderful for kinaesthetic learners, although I have to be careful to specify how much space the gas takes up, otherwise we have stray particles that disappear out of visual or aural range! We practice solid, liquid and gas a bit and then I shout out ‘melt’, ‘freeze’, ‘evaporate’ etc. and the children stand in position or move around accordingly.  It also provides an opportunity to talk about sublimation, a less well-known phase transition directly between solid and gas, e.g. for carbon dioxide (dry ice) or iodine.

We had a discussion about heat sources and the children drew different heat sources on pieces of paper, e.g. the Earth’s core, the Sun, a hairdryer and even a phoenix (we didn’t discriminate against fantastical sources).

The solid-liquid-gas game was a great introduction to talking about conduction, and then other methods of heat transfer. We modelled conduction in a solid. The children stood in a line and I told them there was a heat source (like a fire or a hairdryer) at one end. The child closest to the heat source started to wobble, then the child next to them, and so on, like a Mexican wave. (It probably helped that they had done similar activities at the start of the term for transverse and longitudinal waves.) We didn’t really model convection or radiation but we talked about them and then went to look at a worksheet of different situations where heat is being transferred. (I don’t expect the children in my classes to do much reading or writing but we do have worksheets occasionally.)

# Electricity

There is very little about electricity in the NSW primary syllabus. Children in Stage 3 (Years 5 and 6) are expected to understand about sources of electricity and how scientific knowledge can inform the decisions that we need to make about methods of electricity generation and the impact these have on the environment. We covered this part of the syllabus by playing Energy Trumps (pdf) (from the Centre for Alternative Technology in the UK) and, outside of class time, I recommended that children try the Electrocity game online.

In the class I set up various simple DC (direct current) electrical circuits and provided the children with circuit diagrams and a key to the symbols used. The children enjoyed identifying which circuit was which, quickly identified the ones which would not work (due to an incomplete circuit or lack of a power supply) and went on to create their own circuits with simple components.

There is no substitute for letting children actually work hands-on with scientific equipment. I think I am not exaggerating to say that every child enjoyed this class and could have carried on for longer. Maybe another year we will make simple devices for them to take home with them.

## The Physical World: Rainsticks and stoves

This week my younger group (covering the KS1 syllabus) made home-made instruments. This is what our craft table looked like after the activity:

We started off with a recap about sound, given that most of the children hadn’t taken part in last term’s class. One girl played her violin for us and my 10 year old son demonstrated his doumbek (a middle-Eastern drum). He pointed out to the other children that the sound was far better if you angle the drum so air can move out of the base. All the children had a turn on the doumbek if they wanted to.

I told the children that all sound is caused by vibrations. We tried plucking a rubber band, and I stretched it two different ways to show that the same band stretched longer makes a higher note. I got out the copper pipes for my glockenspiel and we had a go at hitting them. To get a good resonance you have to suspend the pipe where the nodes are. (Nodes are stationary points in a wave, i.e. they do not move up or down.)

We briefly talked about the vibration making the air molecules move and then reaching our ears. I also said that the amplitude of the vibration determines how loud or quiet the sound is. However, the amplitude comment was mostly directed at one of the mums so I am not sure whether any of the children absorbed this information.

I then got out my box of ‘junk’ and showed the children the rainstick I had made by knocking nails into a Pringles tube and adding some popcorn kernels. All the children had loads of fun hitting nails into their tubes (wearing suitable safety gear of course). I ran out of popcorn and so I had to give them rice as well.

This is a picture of the inside of my rainstick, with the nails making a spiral pattern.

Some children made other ‘instruments’ with the materials I had provided. However, I think once I brought out my rainsticks, all of them wanted to use the nails, so the instruments weren’t as diverse as I had hoped.

If repeating this class, I would organise it differently. I think I would start off with the box of junk, provide a larger number of materials and a wider range of materials, and challenge the children to find different ways of making a noise with the same object. This could lead into a discussion about how we make music (striking, blowing, scraping, shaking). I would leave the rest of the class far more open and see what instruments the children came up with.

I might not introduce my rainsticks until half-way through so that it was just one option for making an instrument and the children didn’t feel they had to follow my lead. Or perhaps I shouldn’t show them my instrument at all. If we did make rainsticks, I would provide several different types of filling, some small like rice and some much larger, like shells. Then the children could see whether the type of filling made a difference, and decide which kind they wanted to use.

When I am further ahead with my copper-pipe glockenspiel it would be good to get the children to organise the pipes in order of pitch. This would make it absolutely obvious that pitch is related to the length of the pipe (and we can extend to other instruments too).

I also forgot about two activities I had planned – one to get the children to do a kind of ‘mexican wave’ to illustrate vibrations, the other was a small discussion about our larynxes (voice boxes).

Nevertheless, I feel happy with this class as I think all the children enjoyed themselves and learned something – whether about the nature of sound or the skill involved in hammering in nails! I know for certain that one child went home and subsequently experimented with rice and other household items all over the place, and my 3 year old (who sits in on the classes) had plenty of fun decorating herself with sticky circles (which I had provided for decorating the rainsticks).

The older group (covering the KS2 syllabus) this week consisted simply of my 10 yo son mentioned above. But we finally got the chance to make our own soda-can stoves. We went outside to fill them with methylated spirits and try to light them.

These stoves are really easy to make and use everyday materials. Nevertheless we identified two main problems with actually using them: the wind blows them out pretty quickly; and you need something to balance a pot on if you actually want to use them to heat up any food. But my son was so keyed up by just making the stove that he vowed to find the next few days addressing the other design problems. I think this will cover some of the ‘Working Technologically’ side of the syllabus as well!

My two middle sons also had fun making a mini-camp-fire with the spent matches:

Acknowledgements:

I found the rainstick activity on the Satisfied Mind website.

I am following the instructions on instructables.com to make my copper pipe glockenspiel but there are other instructions all around the internet.

The soda can stove instructions were also on instructables.com.