Catastrophic events

The classes are now over, for this term: we have finished ‘Changes to the Earth’s Surface’, and I am looking forward to hearing people’s feedback.

After a week to take measurements, I asked how everyone’s rain gauges had performed. We used the questions I posted already to prompt discussion. It was good to hear the children’s thoughts about what might have gone wrong and how we could improve the design. Many people had not measured any rainfall over the past week – I assured them that a zero result was still important for many reasons. (If adults are interested in reporting of null or negative results you might like to read a discussion on Nature Network, find out about The Journal of Null Results and read some more discussions on negative results here and here.)

We revisited drought and flooding. I showed some little animations from the UK about three different types of rainfall. I think these are simple but comprehensive. We looked again at the maps of annual rainfall again, from the Australian Bureau of Meteorology, that had so baffled the children the previous week. This time we all talked through the key, and looked out for years when there had been loads more rainfall than usual, or far less rainfall. We then watched videos of flooding in 2011 and drought in central Australia (BBC programme from 2008). Some children were a little upset by watching these, but we went on to talk about how people can predict, plan for and cope with these catastrophic events.

After briefly recapping plate tectonics, we covered earthquakes by making seismic waves with slinkys – you can see these explained with simple animations on the BBC Schools website and on some lecture notes from San Diego State University. We talked about how engineers can test structures to see if they will cope with earthquakes. We watched some videos of these ‘shake tables’ and then built structures ourselves with Duplo (TM) and shook the table to see if they would fall down or not. This was a great deal of fun! I think the children particularly enjoyed building structures that they knew would fall down.

Building with DuploDuplo tower

 

 

 

 

 

 

 

The teachengineering.org website goes into shake tables and earthquakes in much more detail if you are interested. There are two lesson plans that look good although I have not tried them out: Earthquake in the Classroom, and Shake it Up!

I read a few passages from ‘The House on the Volcano’ by Virginia Nielsen. We talked a little about how these catastrophic events are explained by pre-scientific communities as being due to supernatural reasons. When relief organisations are trying to help people or to evacuate people from areas at risk, it is important that they take into account people’s beliefs. (For those in NSW, this touches on parts of the syllabus for Human Society and its Environment.)

The House on the Volcano

For cyclones, tornadoes, hurricanes and tsunamis, we started by reading from ‘The Day of the Elephant’, a beautiful picture book about the 2004 Boxing Day tsunami.

The Day of the Elephant

As a challenge, and to find out how much the children already knew about these events, I had prepared paragraphs and pictures of each of these events. These covered:

formation,

what they look like,

how they form,

what damage they do,

how we can predict them

and how we can prepare for them.

I read these out at random, or handed them to the children, and we sorted them into a huge grid on the floor. I think this activity worked well. All the children were engaged, and keen to work out where each piece went. For future classes I may stick them onto backgrounds like a large jigsaw, so a picture is formed when the children have completed the activity.

natural disasters grid

The same session I brought along a home-made ‘vortex cannon’. This is a very fun piece of equipment to make, that shoots a small vortex of air out of the front. We made ours out of plastic milk cartons, one carrier bag, some gaffer tape and some elastic bands. I can’t find the specific instructions I followed, but if you check on YouTube there are many videos of people making and shooting these, some on huge scales.

We also made a ‘tornado in a jar‘ very simply, with water and dishwashing liquid. The children passed this around to each have a go.

On the final week the children gave their presentations. They varied in confidence and it was great to see each child standing up to have a go. I hope all the children and parents felt it was a welcoming and supportive audience listening to them. I loved all of them but wanted to particularly show off the poster that one child made about volcanoes:

volcanoes poster

I had also set up some ‘stations’ to demonstrate a few of the topics we had covered in the classes, so that the children could take their parents round and explain everything to them. The most popular was making the sedimentary rock models disintegrate by pouring water on them (simulating weathering and erosion). I forgot to bring everything, particularly the ‘bones’ from the Xenosmilus activity on Week 1, and I forgot to put out some of the items I had brought along. I apologise if I disappointed anyone.

I think our classes recovered well from the point which was described in my last blog entry. I will devote a future blog post to looking at what I advertised, and seeing if I delivered everything I said I would. I’m sure there are many things I would change when delivering these classes again. In particular, I would spread out the presentations so that there were a few each week for the last three weeks, rather than all in one go. But overall I felt it was a great success.

Next term I will scale back again, and only offer Friday classes in my house. We will be covering materials, the nature of matter and chemistry.

 

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Rain gauges

Making a simple rain gauge:
All we need is
  • a tin can or a plastic bottle with a flat base,
  • a funnel with the same diameter as the can,
  • some paper clips or tape,
  • some slips of card
  • and a ruler marked with mm.
rain gauge parts
If you don’t have a funnel you can make a simple one by cutting off the top of a plastic bottle. It is important that your makeshift funnel and the can have the same diameter at the top, so you know over what surface area you are measuring your rainfall.
I think it is also important that the container has a flat base, however, many designs use plastic bottles with rounded bases. If you think your child will not mind whether the measurements are precise or not, do the simpler designs with a plastic bottle and don’t worry too much about the shape of the base.
Instructions.
Invert the funnel into the can. Clip or tape it on.
rain gaugeclipping on the funnel
Place the rain gauge somewhere in the open, away from overhanging buildings or vegetation, and anchor it somehow e.g. by fixing it onto a post or by sinking it in a bucket of sand, or using a larger container with rocks in.
Choose a time of day when it will be easy to make your measurements, i.e. you will be awake and you are fairly sure you will be at home most days.
Make a prediction – how much rain do you think you will get in your gauge each day next week? If you like, you can also check a weather report each day and see what they predict. (Try to use the same website or news channel so that you are consistent.)
Making your measurements
Try to do this every day at the same time.
If you find leaves or other ‘foreign’ material in your rain gauge, make a note as this might have affected the measurement for that day.
Dip your card into the container so that it reaches the bottom and the water soaks into the card.
rain gauge measuring water level
Take the card out and mark a line where the water stopped, then use your ruler to measure the height of the water level in mm.
rain gauge water level in mm
Tip all the water out to reset your gauge for the next day.
If you miss a day, leave the water in and just make a measurement the next day. Then you can divide by two to give an average for the two days.
Results:
If you want, you can keep the pieces of card, write the date and time at the top and draw a line to show how deep the water was. Then you can arrange them as a ready made bar graph.
Or you can use graph paper to make a rainfall chart.
To think about:
(1) Why did we use a funnel? What difference might it make to the measurements if we didn’t have a funnel? (If you really want, you can make two rain gauges, one with a funnel and one without, and compare the measurements from each of them.)
(2) Why is it important to put the rain gauge away from buildings or vegetation? What difference would this make to your measurements?
(3) How much rain was there in your gauge each day? Did this match your predictions? Did it match the weather report?
(4) What do you think would be the measurement on a day when it had been raining for most of the day? What about a day when it rained for a little in the morning and then was sunny for the rest of the day?
(5) Did you have any practical problems with the rain gauge, and with taking measurements? How might you be able to fix these?
Many simple rain gauges for children just say to cut up a plastic bottle and invert the top part into the bottom. This is good because you are able to see the water in your container, but the measurements then become very imprecise. I like this version because the sand in the bottom both helps to anchor the gauge and also gives a flat base for measuring a precise depth. However I am not sure about measuring the precipitation every day by tipping it out. It seems to me that it would become quite inaccurate because you would have to refill it with just the right amount of sand and water each time.
www.weirdsciencekids.com Rain Gauge
I like the diagrams on the first page of these instructables but you really don’t need the rest of the pages. If you make sure the container has a flat bottom you don’t need to do any conversions between volume and height. (This is, however, the way commercial rain gauges work.)
RIM7499 Professional Grade Tipping Bucket Rain Gauge