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Science Spin March 2009
The 'sticks and balls' approach to teaching chemistry
By Tom Kennedy
Professor Declan Gilheany, a chemist from UCD, described at the SFI Summit last Autumnn how when he had visited a number of primary schools, in order to try and interest pupils in chemistry, that a 'sticks and balls' teaching method proved to be very popular with the children. This could help pave the way to the launch of a national science education programme.
Teaching primary school children chemistry by allowing them to 'build' their own molecules, such as the ethanol molecule pictured here, has proven very successful, according to UCD chemist Professor Declan Gilheaney, who has tried out the strategy on pupils in a number of schools.
It all began, said Prof Gilheany, "when my daughter asked if I could go into her school to talk about what I do." Prof Declan Gilheany is a chemist at UCD, so obviously he had to say something about chemistry, and while thinking about what to do, he remembered how atoms and molecules were often described in the past by stick and ball models. Computer modelling, among other factors, had led to a decline in popularity, but it struck Prof Gilheany that sticks and balls could be the ideal way to explain chemistry to primary pupils.
Armed with his box of stick and balls, Prof Gilheany gave his talk, and as he explained, the reaction was amazing, "completely over the top." The class had no problems grasping the concepts, and they enjoyed discovering how different kinds of "stuff" can be built up from atoms.
"I was very surprised by how successful it was," said Prof Gilheany, so he began thinking that this approach to teaching chemistry should be taken more seriously. He looked up teaching contacts through the Forfas Primary Science and SFI websites, so that he could visit more schools. Over the last three years Prof Gilneany has been to 12 primary classes, 2nd to 6th class, and each time the chemistry kit was a big hit with pupils.
Kit
The kit is quite simple, and it consists of coloured balls with plastic connectors. The balls follow the long established convention of black for carbon, red for oxygen, white for hydrogen, blue for nitrogen, yellow for sulphur, and purple for phosphorous. Each ball has the appropriate number of holes for the connectors, so atoms cannot be joined up in the "wrong" way.
No doubt, one of the reasons for the success of these lessons, is Prof Gilheany's well-paced delivery. He obviously enjoys teaching. "You start by asking, what is everything made of?" Naturally, the term 'stuff' is quick to emerge. "So what's 'stuff' made up of?" he asks, and that leads very easily onto the idea that its made up of molecules, and that molecules in turn are made up of atoms.
By now the pupils are curious, so Prof Gilheany then surprises them with the news that there are about 100 different atoms, and not only that, but if you join them up in different ways you can get all sorts of molecules."Then I ask them if they know the structure of water, and quite a few do, they know that water is H2O, so I take up three balls, my oxygens and a hydrogen, and join them up." To the pupils seeing this happen before their eyes is like a miracle.
Eager hands take hold of the kit as Prof Gilheany hands over the box telling the pupils to "go on, make a molecule, and I'll tell you what it is."
The simple molecules come first, and as Prof Gilheany said, methane is one of the most popular because it comes out of a cow's rear end. Then there is salt, which they all know, ethene from bananas, the SiO2 for sand, carbon dioxide, butane from the gas cooker, chlorine from the swimming pool, and lots of others.
Molecules
"Then, you move on to the more complex structures", he said, and the pupils start to work together to make fats, proteins, sugars, diamonds and whatever else takes their fancy. Prof Gilheany knows his molecules, but even so, he said it is really important not to pretend to know everything. "It can be a case that the molecules they come up with do not yet exist," he said, and factors other than simiple stick and ball chemistry come into play. A little bending of the facts, he said, can be required, but "always stay close to the truth, because kids know when you are faking."
Questions start to come up on why should some atoms have more connections than others, and that, said Prof Gilheany, leads on quite naturally to the concept of valence. "For valence," he said, "I talk about methane being burned and producing carbon dioxide."
The explanations act like a catalyst, and Prof Gilheany said that after leaving one particular class in Trim, the pupils got busy in an attempt to build the world's biggest molecule.
"After each talk," he said, "I am completely shattered because every child has lots of questions, and you have to respond."
The existing stick and ball kits, he observed, do the job, but he believes they could be improved, and the positive response suggests that we should now think of launching a national programme to bring chemistry into primary schools.
