Talking Teaching

October 3, 2010

engagement techniques for teaching evolution

I see we’ve had a few hits recently from searches for teaching evolution. This is a topic that’s of particular interest to me, and while I’m definitely not an expert in the area of lifting student engagement with this often-contentious topic, I thought I might write a bit about some of the approaches we’ve tried here, plus some of the literature in this area. So pull up a chair, it could be a long-ish post :)

Teaching evolution can be fraught with difficulty: it is probably the only scientific theory to be rejected on grounds of personal belief. And beliefs can be very hard – perhaps impossible – to change. My own feeling, which fits with how I feel about teaching science in general, is that we should move from simply teaching a series of facts and concepts to looking at the development of the theory of evolution, and placing it in its social and historical contexts. After all, simply listing the observations & postulates that support Darwin’s concept of natural selection as the driver of evolutionary change isn’t exactly calculated to win hearts & sway minds! But helping students learn how our modern theory of evolution has developed over time may lead them to understand evolution, and so move beyond their various misconceptions around the topic.

There’s now a large amount of literature looking at the teaching of evolution. Back in 1994, William Cobern commented that “[teaching] evolution at the secondary level – is very much like Darwin presenting the Origin of Species to a public who historically held a very different view of origins.”  He felt that to meet this challenge, “teachers [should] preface the conceptual study of evolution with a classroom dialogue … informed with material on the cultural history of Darwinism.” In 1995 he added “I do not believe … that evolution can be taught effectively by ignoring significant metaphysical (i.e. essentially religious) questions. One addresses these issues not by teaching a doctrine, but by looking back historically to the cultural and intellectual milieu of Darwin’s day and the great questions over which people struggled.” Of course, the key issue here for classroom teachers is time – how on earth can all this be fitted into an already packed curriculum? (Well, that’s one issue – an equally pressing one is probably: where are the resources to support teachers in doing this?)

One answer lies in the changes to the NZ science curriculum, which is underpinned by a focus on the nature of science itself. You might remember that I wrote a bit about this in an earlier post. Part of that requires that students “learn about science as a knowledge system: the features of scientific knowledge and the processes by which it is developed; and learn about the ways in which the work of scientists interacts with society” – in other words, an understanding of the history of science is crucial here. And the ‘evolution back-story’ offers an excellent opportunity to learn about that, and also about the way science is done. Mind you, it also necessitates a change in how the topic is taught: one that gets students actively involved – not least, in examining their own conceptions of the topic. (My friend Kathrin Otrel-Cass & I discussed all this in a recent paper of our own.)

This was something I was very much aware of when I was redesigning our second-year paper ‘Evolution & Diversity of Life’. And that was a tricky balancing act! Pressure on the one hand to keep/increase the ‘diversity’ content, to support various third-year papers; and on the other, pressure to include more genetics; and in the middle, me, wanting more of the historical/philosophical stuff – completely necessary, given around 10% of students in the paper tended to a creationist view on the origins of diversity. Anyway, I read around a lot, & at the time I was quite heavily influenced by the work of Passmore & Stewart, who’d looked at practical ways of increasing student engagement with and understanding of the subject. (Tonie Stohlberg (2010) has also discussed such an approach, although I’m not entirely in agreement with her on all counts: for example, the statement that religion promotes a sceptical approach as much as science does. This sits uneasily with the faith-based nature of religious beliefs.)

In their 2002 paper, Cynthia Passmore & Jim Stewart discuss an evolutionary biology course that they designed, based on earlier classroom research and with 3 main principles underlying it:

  1. “There should be a commitment to designing instruction around key models [in this particular case, natural selection] in the discipline under study.
  2. There should be a recognition that scientific practice is discipline specific. The development of a curriculum should therefore take into account the ways in which scientists operate within their fields.
  3. There should be a commitment to providing opportunities for students to develop, revise, and use models in ways that are true to the discipline.”

Passmore & Stewart discuss the nature of scientific models at some length – something that’s directly relevant to teaching the nature of science in NZ classrooms today. In fact, they comment that they “believe that organising curricula around sets of scientific models provides students with opportunities not only to learn about the conceptual subject matter of particular disciplines but also about the natre of scientific knowledge – how it is constructed and justified…” Their course also gave students the opportunity to examine things like language use and scientific methodolgy as they built up arguments around an historical event. I liked this approach, not only because emulating it would hopefully enhance my students’ understanding of evolution, but also because of that very emphasis on understanding the nature of science (NoS). (A colleague and I had done an informal survey of our students’ understanding of the NoS & found it lacking, so you can see why I was keen to improve on this.)

Because of the multiple pressures on the paper I had to be selective: we couldn’t adapt Passmore & Stewart’s program in its entirety. In the end, we combined a range of activities that enouraged the class to: work collaboratively, build models, discuss ideas, and defend their position. This included a session using Rob Gendron’s exercises based on the Caminalcules, intended to get students thinking about the evidence for determining relationships between groups of organisms, and  the ways in which organisms might change over time. (The Caminalcules are rather hard-case, & because they look nothing like any animals students will have experience of, there’s less chance of preconceptions around relationships affecting the outcome.) While fun, it also required students to explain and defend their decisions. Another class had them reading & discussing work by Paley, Lamarck & Darwin (as described by Passmore & Stewart) & then analysing these models to identify the assumptions made by each author – & also their shortcomings. The idea here was to allow the class to identify some of the common misconceptions around evolutionary theory, & hopefully to avoid them themselves. It led on to a deeper examination of natural selection, based around some other work from Rob Gendron: a simulation of the action of natural selection, that you can expand on by introducing things like variation & mutation into the discussion. And we originally  finished up with a role play, where students took on the role of mediator & protagonists in a creation/evolution debate (script from a debate broadcast in the US some years ago). Then a couple of years later the PBS documentary on the Dover trial came out, & we used that instead as the starting point for a discussion around the nature of science. (This section of the course was definitely not your ‘typical’ university science lab course!)

The class members certainly seemed to appreciate this approach. They commented (in the end-of-semester appraisals) that it was more interesting than ‘standard’ labs, and made them think harder about the topic; they also valued the fact that it was non-judgemental/non-threatening. (I’ve often thought that  putting someone in a situation where their personal beliefs are threatened is hardly a way to bring them round to another point of view.) They were certainly more actively involved – more engaged – with what was happening in the class, although because we didn’t have both pre- & post-tests in place I can’t put my hand on my heart & say that there was a long-term change in attitudes & understanding. That’s something we need to implement as part of the next revision of the paper. And this time round, of course, I’ll have the benefit of Craig Nelson’s 2008 paper on techniques for engaging students in classes, particularly those on evolutionary biology. But I think the program would have enhanced their appreciation of the following video, which has been doing the rounds on the various SciBlogs sites lately!

A.Campbell & K.Otrel-Cass (2010) Teaching evolution in New Zealand’s schools – reviewing changes in the New Zealand Science curriculum. Research in Science Education 40 (published on-line 21 April 2010). DOI: 10.1007/s11165-010-9173-6

W.Cobern (1994) Point: belief, understanding, and the teaching of evolution. Journal of Research in Science Teaching 31(5): 583-590

W. Cobern (1995) Science education as an exercise in foreign affairs. Science & Education 4: 287-302

C. Nelson (2008) Teaching evolution (and all of biology) more effectively: strategies for engagement, critical thinking, and confronting misconceptions. Integrated and Comparative Biology 48(2): 213-225

C.Passmore & J.Stewart (2002) A modelling approach to teaching evolutionary biology in high schools. Journal of Research in Science Teaching 39(3): 185-204. doi: 10.1002/tea.10020  

T.Stohlberg (2010) Teaching Darwinian evolution: learning from religious education. Science & Education 19(6-8): 679-692. DOI: 10.1007/s11191-009-9187-5

March 19, 2010

Mobile phone physics

Filed under: university — Tags: , , — Marcus Wilson @ 3:51 pm

This post is a copy from my (Marcus Wilson’s) blog physicsstop. ( )

Just occasionally, I have a crazy thought regarding a physics demonstration.   This is one that I’m thinking about inflicting on my third year electromagnetism class.  

We’ve been discussing the way electromagnetic waves travel (or rather, do not travel) through electrical conductors. Basically, conductors allow electric currents to flow in response to an applied electric field (in simple terms this just means applying a voltage). Electromagnetic waves such as visible light, radio and X-rays contain electric fields, so when one hits a conductor electric currents flow. Flowing currents heat up a material. Where does this heat energy come from? From the wave. In other words, conductors suck out energy from an electomagnetic wave, and, broadly speaking,  the wave can only penetrate so far into the conductor. This distance is what’s known as the ‘skin depth’.

Skin depth depends importantly on two things – the conductivity of the material and the frequency of the wave. The higher the conductivity, or the higher the frequency, the smaller the skin depth.  Thus, if you consider the waves to/from a mobile phone (frequency of around 1000 MHz) travelling through aluminium (a very good conductor) the skin depth turns out to be small indeed – microns in size.  That means wrapping a phone in aluminium foil will prevent it from picking up a signal. I’ve already shown this in class.

But – here’s the crazy thought – what about water?   Distilled water is a pretty non-conductive, but what comes out of the tap is loaded with dissolved salts and has a moderate conductivity, albeit several orders of magnitude below aluminium foil.   What’s its skin depth for  mobile phone frequencies?  I’ve done some quick back-of-the-envelope, and I reckon something of the order  few centimetres.  So….I predict that if we put the phone in just a few millimetres of water (YES, it needs waterproofing first!) it will still receive a signal, but suspend it in the middle of a swimming pool and there’s going to be no reception at all.

 I reckon that getting my class to estimate how much water would be required to shut out the signal, and then design an experiment (that might or might not need to include ‘borrowing’ the university swimming pool for a short while) would be a great way to get them to think about the various issues themselves.  There’s plenty of literature to back up that assertion – e.g. Etkina et al., American Journal of Physics 74(11), p979  (2006). The best thing is that I can’t be tempted to tell them the answer –  because I don’t know it – I haven’t done the experiment myself. Though I have found this YouTube…

« Newer Posts

Blog at