Expert Insights

When you think of things in terms of energy you can represent energy … energy can be modelled as a particle, as matter.  It can be modelled using waves and then trying to talk about how we would use each model as it's appropriate for a particular situation.  It's the sort of things we observe might dictate which model we use to explain it, by recognising that in each case there is another model but perhaps just not as useful.  So maybe it goes back to just trying to show that everything that we do is a model, every model has its upside and its downside and that we usually only use a model that’s as detailed as it needs to be for the particular concept that you're trying to get across.  If you want to get across a concept of a car to someone who has never seen a car you don't probably show them a Ferrari or a drag racing car.  Maybe you show them a Lego style block and we do the same thing with our scientific models as well.  I guess trying to get across that idea that this is the model that we're going to use but it can be a lot more complicated.  I don't want you to think it's as simple as this but it's appropriate under the circumstance.  So I guess I spend a lot of time talking about things as models when I'm talking about quantum mechanics.  Our treatment in the first year, which is where I cover it, a little bit of second year but I don't take a mathematical detail treatment of quantum mechanics.  Someone else does that, so I really bow to them. So most of mine is non-mathematical, just simple mathematics and mainly conceptual type of stuff.  I guess some of the things I try and do to illustrate the differences between the models and the way that we use them is to ask questions in class that might be postulated in such a way that you can't answer it if you're thinking about both models at the same time.  So the one I like is where I show say a 2s orbital and the probability distribution of that node in between.  I talk about things that … there's one briefly, this plum pudding model which they all laugh about.  When you look at this 2s model there is a probability and a high probability, relatively so, that the electron can be inside the nucleus, if you think about it in particle terms.  Then talk about the nodes and so on and how they arise in quantum mechanics and so on and then ask questions like if the electron can be here and here but it can never be here how does it get there?  ...  I try and get across maybe the bigger picture, everything we're going to do from this point on (because we do this fairly early in first year)  - everything is going to be a model.  Nothing is going to be right.  Nothing is going to be wrong. Nothing is going to be exactly the way it is.  Everything will be just a model. You'll hear us saying things like ‘this is how it is’ or ‘this is what's happening’.  But really you need to interpret that as ‘this is a model and this is how this model is used to explain this particular phenomenon.

It now does come down to the quality of the presentation in terms of what you put on the PowerPoint I suppose, cos we all use PowerPoint.  But I try most lectures to switch that off and use the visualiser and write things down by hand, where I can see that something is missing on the PowerPoint, or if I think the students haven’t got a particular message, don’t understand a reaction, don’t know about a mechanism. I’m happy to stop, go to the visualiser and write it down at the correct sort of pace, by which they can actually write it down themselves.

Many years ago, lecturers only had one style, you know they just wrote on the blackboard, actual blackboard with chalk.  That was the only style.  They just talked... That’s all I knew so that was fine and so I thought, well I’ll just continue that and the students weren’t understanding what I was saying and explaining and I thought, oh hang on what’s going on here?  This is the way I was taught.  Come on, it should work.  So, yeah I think it would be good if someone told me that at the start, but as I said because I’d end up doing my Diploma of Education that opened my eyes to that and that’s when I started to utilise different strategies and I appreciate that not everyone is going to understand one way of, my teaching way.

So, just to make them do some work, and made them think about the ideas themselves.  Talk amongst themselves about it.  I think that just too much of me in the lecture just washes over them after five to 10 minutes.  So they just need to have a break, think about the problem, do a couple of problems, talk amongst themselves... that seems to help, with both the variety of students in the class, but also just keeping them engaged.  Keeping their attention.

I think it’s really important that people mark assessments.  Mark, and see what the students actually end up knowing.  Because they can pretend to themselves that students have understood everything, but if they actually have to mark the exam papers, or the quizzes, or whatever it is, they actually are confronted with the students actual knowledge.  I think that’s really influential.  The second semester of teaching, when you think you’ve explained things well, and then 90% of the class have not got it, then it’s not the students fault at that point, it’s probably your fault.  So I think that assessment is really important.  Not only for the students, but also for the marker.  I think you can learn a lot from marking.

When we’re teaching ideas in chemistry, I liken it to hacking your way through a forest.  It’s all this detail.... and you can’t expect students to do the hard work of fighting your way through the forest or the jungle, unless they have a global view of where they’re going. What I mean by that is, the other factors that influence the way I teach intermolecular forces, is that I keep going back to applications in the real world.  How is it that geckos can crawl up a wall, and almost sit on the ceiling without falling off?  How is it they’re able to stay there with gluey legs or what?  But the interactions between their feet and the ceiling are just, how could they maximise the attractions between the molecules in their feet, and the molecules in the ceiling? So what I’m trying to do all the time is to show applications, powerful, interesting, hopefully, and engaging applications of the ideas that are important. So, for students to engage and to feel, ‘well this is worth hacking my way through the jungle of detail to be able to understand it’, is to zoom out and show them how this topic relates to all of the other topics.  It’s called scaffolding, and it’s a very, very important idea. So, the other factors are essentially the incredible number of other applications of this idea... that the power of an idea is its explanatory power, and when they can see just how important an idea is, in being able to explain all sorts of phenomena, they might be willing to care about it more.

In the lab it comes out in a variety of ways.  It comes out most commonly when the student gets to actually start doing their calculations and you ask them to relate that back to what they’ve actually physically measured.  And when they start doing those sorts of things you realise there’s a bit of a misplaced idea here or a misconception that you can deal with there.

They struggle with the language of chemistry.  So we sort of need to teach them the process and how to work out how to do these things.  We know that their tendency is just to attempt to memorise reactions.  Whereas if we can teach them to derive … find out what the nucleophile and the electrophile is then all they have to do is draw a curly arrow from the nucleophile to the electrophile, rather than trying to work out what the reaction is itself. 

It’s continuous learning.  I mean, what I used to try to say to students when I taught the acid-base stuff I’d say ‘look there are only about six types of problems and if you can solve one of them you can solve them all because they’re all the same.’ But what you’ve got to be able to do is look at the question and say to yourself ‘this is one of those types of questions therefore this is the way I should think about approaching it.’  So take the question, dissect it, decide what you’re being asked to do, decide what information you’re given, and then say ‘yeah that’s one of those types of questions, this is the way I should go about solving it.'  If you can get that across to them, that it’s not a new universe every time you get a question, it’s simply a repeat universe of the same type of question... But many students tend to look at each problem as a new universe and start from the beginning again.  Many students don’t see that there is a limited number of problems that can be asked on a certain topic.

So, it’s helping to bed down analysis, problem solving, doing the sort of detective work to get to an answer.  And the students also seem to quite enjoy having material presented to them in that way - here’s a spectrum, what do you think the structure is, because it’s a more active form of learning as well.  So I find I enjoy teaching it, and they respond well in terms of, they keep coming in and asking me for additional problems to practise on which is clearly evidence that they feel it’s challenging them.

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