Expert Insights

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.

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.

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

At the start of every class my standard thing was ‘can you see me, can you hear me, can you see the slide?’ I would always look up the back for someone to put their hand up and always I would never talk to the front row. I’d always talk middle and back row and if someone was talking in the back row I’d pick them up and say ‘hey you, be quiet’ and then they know that I’ve seen them.

So you’ve got to focus on the whole class not just the people at the front - the people at the back as well.  Because sometimes smart people sit at the back as well, not just the dummies who want to get out. You’ve got to make sure you know everyone in the class.  And the surprising thing is that most kids sit in the same place every lecture.

So you can actually recognise where they are and who they are.  You don’t know their names but there’s a pattern in the way they sit.  You’ve just got to be aware of that.  So the trick is to embrace the whole class with your - you know physically, just with your eyes and and the way you talk.  You know, when you wave your hands, wave it to the back row. Make sure they’re involved.

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.

Try to show students that the fundamental form of matter is energy. Then that this can be represented as particles with mass or as waves (wave functions). Then try to show them that we use the model particle/wave that best helps us understand different phenomena. In class I often do this by asking questions about wave mechanics in particle terms. eg. If a 2s orbital has a node how can the electron pass accross it? Then explain to them the limitations and advantages of each approach.

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 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. 

I was thinking about Le Chatelier’s principle and how that’s quite cumbersome in its wording, and so when I teach it, and how I always break that down into language that’s probably easier for students to understand, and Bob tells me that’s called repackaging, and I sort of thought that through all my teaching I do a fair bit of repackaging, a lot of the time, so I guess that was just a trait that I use and has been pretty successful for me, I think.

We all spend a certain amount of our class time going through definitions and jargon and getting students up to speed with the basic area and now that’s material which I take out of the class and put online and let students read and understand that in their own time before they come to the class.

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