Expert Insights

I started lecturing before I did my Diploma of Education and I would have recommended to all of the lecturers to do it because it really helped me in my teaching.  Mind you, I already had a bit of experience, I don’t know, you know, the chicken or the egg type thing.

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.

When they come in I give a very simple quiz which we do using clickers, the sort of anonymous audience response systems, and I just test a few multiple choice questions, just testing their understanding of some of those terms and then when I notice that there’s, well, anything more than 10 or 15% of students who don’t correctly understand those terms then we go through a process of exploring what those terms are and why they apply to what they apply to and then I retest that a couple of weeks later.... I notice at the end of the year some of the students can lapse back into their old habits, so it’s something that I am going to need to think of continuing to reinforce.

Students should [only] be limited by students' curiosity.

So you shouldn’t be rigid, you shouldn’t be rigid in what you’re going to do.  It’s always stunned me that people say you should know where you start a lecture and where you’re going to finish, and if you get to that point and you finish ten minutes early you then should just finish.  I’ve never worked on that principle.  I never know where I’m going to start because I never know where I’m going to finish, right.  So where I finished the lecture before is where I start the next day, I haven’t got a set content.  If a student asks me an interesting question and I get the feeling that they want to know that answer I’ll go off for five or ten minutes or three or four minutes answering it, and if I don’t get to the end of where I thought I was going to get to, too bad I’ll do it next time.  So you go with the flow, you don’t go with a rigid thing ‘I’ve got to get through these 15 slides today and if I don’t the world will end,’ because it won’t.

I like to approach chemistry as a different language, because it used symbols to convey ideas across, but they are not the reality.  When we draw a little stick structure, alcohol does not exist as I’ve just drawn it, it’s a representation.

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.

The concept of a continuum is, I think, really important in chemistry and… what I see is that students come up with this issue of things being black or white.  They struggle with this concept of the in between stuff.

I guess what every educator deals with is needing to find out what preconceptions there are at the start of the unit and then correct those and then keep on top of those throughout the course.  For example I get students who use the word particle and the word droplet interchangeably. Whereas to an expert, a particle is something that is made of a solid material and a droplet is something that’s a liquid material.  Students use those interchangeably so they may be talking about a suspension of solid materials but then they use the word droplet because they think it’s interchangeable with the word particle. Or vice versa, they might be talking about an emulsion and they talk about particles where they should be talking about droplets.  So because they’ve heard these phrases before in first year... the importance of using exactly correct terminology hasn’t been reinforced.

In the lecture theatre the best strategy there, where you’re confronted by all the constraints of the lecture theatre, is to stop and do stuff with the students, walk around amongst them, see what they’re actually doing... And out of that you might go back and address some aspect of it and revisit it or something like that or you might point them to some tools to use to work out some other aspect.  So in the lecture theatre it’s very much for me a case of stopping and going and seeing what they’re doing and if you don’t then clearly you don’t know. 

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