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.

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.

They [students] reveal great misunderstandings about the molecular world. So the difficulties and limitations are as a result of not spending sufficient time on getting them to think about this world, and spending too much time on doing. You know, we’ve got to spend some time, but you can’t spend too much time, I think, on a lot of the ideas that we do teach, and doing calculations and things that, really, no one else does. It’s really something that’s done almost like it’s make-work-type stuff.

I think it’s a key teaching topic, also because it’s teaching students to look at data and to interpret data, to assess which part of that data is going to get them to the answer and which part is exquisite detail that they can come back to later on. 

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.

The culture in the chemistry department was always lots and lots of content.  And that’s changed now because you don’t need it, because they can find it another way, but you’ve got to give them the framework to understand the content.

I think to get the students to straight away mark for somebody else what they’ve just done and then to mark or take part in the marking of two other versions of the same thing is really powerful.  So it’s not so much me directly finding out what they do and don’t understand but using methods by which they can diagnose for themselves.  I haven’t got this, she has, or yep I have got most of that, she hasn’t, and I can see where she went wrong.  Very powerful, very powerful indeed. 

A lot of it is from colleagues.  Conferences are fantastic.  You know, your chemical education conferences.  I do go to a lot of those.

The big picture is that in any topic there’re key principles, and if you as a lecturer can get across the key principles, that then sets them up to solve problems and to think about the other principles and how they connect.  But if they don’t, if they’re not prepared to accept the fact that there are these key principles you need to understand then it’s not going to work.

So the strategy is to reflect, to change things, to be flexible, to talk to them but not talk down to them, and certainly I would say to any young lecturer don’t be writing the lecture the night before. Know what your course is because then you can jump back and forth as you talk about something.  You can say yeah we talked about this a week ago or something like that, you know. Know what you’re going to talk about, the whole thing, because then you can put it all together as a package.

Pages