Modelling science

A practical look at using computer models in science (Interactive Magazine 1997).


If you want to know how useful models are, ask a teacher of science. When you need to explain something tricky like waves or molecules you reach for a ripple tank, a Slinky spring or a tray of marbles. Models are part of the teaching kit and so are the words, "Well kids, it’s a bit like this…"

For example, you shake a tray of marbles and you say you’re giving it energy and you’re turning liquid into gas. You discuss the connections between the model and the real thing, as well as talk about the limitations and the assumptions you’re making. It is just a model, you say.

So models are used in science and they’re very useful. And when you get a computer you naturally start looking for software that will help teach this and help model that. The idea of getting say, a spreadsheet and building a model up from scratch - something very useful you might do, is a bit further away.

But if you have seen an ancient BBC program called ‘Moving Molecules’ (CUP - but out of print) you’d push that idea even further away. It does that activity with the tray of marbles pretty well. It shows how molecules behave when you heat them, when you change the volume and when you up the pressure. Sure there’s not much here to develop IT skills, but there is a useful amount of interaction and some scientific discovery too. It’s just a model and it’s just on the computer.

Computer models can enhance - that’s the word for it - science teaching in other ways. These programs can speed up time so that you can say, breed generations of butterflies and study their genetics in the space of a lesson. They allow you to do dangerous things such as pull the control rods from a nuclear reactor, or put a human in the Arctic. They let you do difficult experiments where you need to change and control lots of different variables. Computer models help for quite a mixture of good reasons

Modelling isn’t just for the older pupils. You can find models for infants and juniors - and they often masquerade as adventure programs. In Zoo Keeper (for PC/Mac - Ablac) for example, the children play the zoo keeper. They have to ensure that the animals in the zoo get the food they need and stay away from dangerous animals. And in Badger Trails (Arc - TAG) junior age pupils try to return the badger back to its sett. There’s even some scope here for those IT points about models - like how real are they or what’s not so real?

Another title is At Home with Wattville (Arc/PC - from Understanding Electricity) which looks at the use of electricity at home. It would suit ages 10-12 and it comes with teaching materials - which is a rare blessing. So there’s a meter ticking away under the stairs - and that’s costing them money. The children ‘visit’ rooms in the house and they turn off the things that aren’t needed. And all sort of good science questions arise from this - like what costs a lot to run, and what we can’t do without.


A more recent favourite is Exploring Nature (PC/Arc CD-Rom - Hampshire) which lets the children ‘out’ into the garden, forest and meadow to explore the wildlife there. As they explore they can take ‘photographs’ and make notes. They can read about the flora and fauna in a built-in nature study book. They can even use a thermometer and a light meter to take readings in each environment. They may even be able to relate these results to the kind of wildlife in each habitat.


There’s some scope in these examples for doing what the National Curriculum is about: there’s the analysis of a situation and the testing of ideas. If the pupils understand their model, they can start to look at its limitations. But although these examples allow them to change the data of a model - i.e. to change what happens - they don’t really allow them to change the rules within the model, something the curriculum asks for but doesn't explain why.


Nutrition

You will find many diet analysis programs in the software catalogues. Their usual approach is to start by asking you to type in the foods you have eaten over a period of time. They then total the amount of each nutrient in your diet. They may also draw graphs of this and maybe also show how well you are matching your personal nutritional needs.

These are examples of a model of your diet and they let you change things - to see the result of eating less eggs or eating more fruit. You can even change your age, which of course is really nice, and see how that affects your body’s requirements!

Strangely, very few diet programs seen have the right balance for school use. Diet Guide (for KS2-3, Hampshire Arc only) is an exception. (That’s despite it’s crazy professor character - not the role model we like to promote). Those who have Microsoft’s Encarta encyclopaedia (Age 14-18, CD-Rom for PC/Mac - mail order) should take a look under its nutrition topic. Here you’ll find some diet analysis tools which are quite promising for the classroom.

Electronics

Crocodile Clips (Disc PC - CrocClips) is a program which lets you build circuits. You can start with a simple circuit using just a battery and a bulb. You can add more batteries and then see what happens. You can build quite sophisticated circuits with all sorts of electronic components and then place a meter or an oscilloscope in the circuits.

This is no substitute for doing the real thing but the program presents opportunities to explore circuits in a unique way - like test components to destruction. It would suit those at age 14 plus, in science or electronics courses. Another program Edison (PC - shareware, hard to source) also has some very mousy drag-and-drop type of circuit building and it’s well worth hunting down.

Motion

A really special program Fun Physics (Disc for PC/Mac - TAG) is perhaps one of the best modelling examples. You may have heard of its grown-up edition called ‘Interactive Physics’. Here you build and play with models on the topic of motion. You can draw a ball and then drop it down the screen. And you can draw a box underneath it and watch it bounce on top. You can change the material of the block, or change the gravity. You can even hang the ball from a string or a spring and graph the effect. This title, for ages 13+, ‘tickles’ much of the IT curriculum on modelling.

Cardiovascular System

Cardiovascular System (Disc for PC/Mac - TAG) is a graphical model of the blood system. You can get a model person to ‘run’ and show the pulse rate and blood pressure on a graph. If you’ve got some mean tendencies you can inject arteries with adrenaline, cut them open and them provide a blood transfusion. As you study fitness and heart disease you can take readings of blood flow, oxygen and carbon dioxide levels.. Incidentally, this does all of what the NC is asking - but it’s quite hard for GCSE pupils, and even nearly too hard for advanced level.

For more examples of this sort of software in this same series, as well as many others, the Association for Science Education do a couple of books of mine called "IT in Primary Science and IT in Secondary Science. I’m biased but they collect together the ideas and resources needed to cover all areas of the science curriculum.

The DIY option

There’s another approach to modelling science on the computer which doesn’t require lots of extra software. You or the pupils can create models from scratch using a spreadsheet program. For example, the pupils can build a model showing how much electricity the school uses. (see pic). Each line in the example calculates how much electricity is used in a part of the school. At the bottom you can see the total electricity used.

You can play with the model too: you could switch everything off and save a fortune on electricity. Or you could look for places where you can make economies. You could size up the savings possible and decide whether to install sensors which switch on the lights when rooms are occupied.

What’s special about this DIY model is that you have a lot more control over how things work. In this example you can alter the price of the electricity, or take into account more appliances or consider the effect of shifting the school day forwards or backwards to make use of changing daylight. In essence you have created something which is very flexible. And more than this, if the children are involved in building models, there’s a excellent chance that they’ll understand how it works. They may also gain some skill with IT that they can use to develop other models.

Of course, pupils will not get here - making, evaluating and extending models in one go. There’s progression to consider - not just the ‘what a spreadsheet is’ and ‘how you type this in’ angle but also the ‘what a model is’ and ‘what the model can do for you’ angle. What this means in practice is that children need to start with models which are ready prepared.

Don’t worry, that doesn’t mean lots of work trying to think up and then create new models. I’d recommend secondary schools hunt down the inexpensive packs in the Essex Spreadsheet series each with several worked examples. For example one pack comes with ready-made spreadsheet models examining electricity and insulation in the home, surface area to volume ratio in animals, and the braking distance of a car. A home insulation model (see pic) tells you how much money you’d save on energy bills by draught proofing and carpeting the house. Draught proofing is far more effective by the way.

The Essex examples all require Microsoft’s Excel spreadsheet, and they use some of its tricks to create models which 11-12 year olds could use. Even if you use some other spreadsheet package it’s worth looking at these for two reasons. One is to see how they are put together so that you might do your own, the other reason is to see the things that science teachers focus on.

You will find another fine set of exemplar models in The Warwick spreadsheet system (PC/Mac from Amo). This is a huge and unique piece of add-on software for Microsoft’s Excel spreadsheet. The First Biology Pack, for example has spreadsheets on diet analysis, predator and prey relationships, breeding wheat, natural selection and genetics - all required at the top-end of the secondary school. What is remarkable is how these exploit the power of a top-end spreadsheet. I do however want to record an open verdict on them: they are pretty clever, and sometimes too clever.

Model builders

Finally There is yet another breed of modelling software, called model builders. Examples include Microworld Project Builder (TAG) and Hyperstudio (Arc/PC/Mac - TAG) - programs which allow you to create models by assembling graphics and by clever use of the tools provided. For example, Microworld Project Builder, a LOGO derivative allows you to place a ‘turtle’ on the screen and propel it across the screen. You can make the turtle look like a car and you can add a ‘slider’ control to adjust the turtle’s speed. If you’re slightly adept with LOGO you can create a stopwatch to time how long the car takes to travel the screen. You might then, with a bit of LOGO-programming see how the car travels with different payloads. It’s quite impressive what you can do with this kind of tool - though it needs programming ability and desperate keenness.

There’s a case for using both ready-made models as well those you build yourself. It’s ironic that these exist to help children understand science and yet once you get involved in modelling you realise that the ideas here are hard anyway. What is encouraging is how well the schools that are tackling this difficult area are doing. When they map out the skills required, introduce them progressively, and give enough practice they get to where they want to.


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