Monday, September 10, 2007

myth-busting: what's a teacher to do?

I just finished talking about the interior of the Earth to my intro class. I drew (semi-)concentric circles. I passed around pieces of peridotite from the Alps. I talked about squishiness in the asthenosphere. I made fun of The Core.

And I'm willing to bet that on Friday, when I start talking about the tectonic origins of igneous rocks, a large fraction of the class will believe that the mantle is liquid. And another large fraction of the class will think that most magmas come from the outer core.

There have been papers in the Journal of Geoscience Education about ways to recognize student misconceptions in order to correct them, and I've tried a lot of the techniques. But maybe there's a fundamental problem with myth-busting.

Last week, the Washington Post published an article about psychology research on the persistence of myths. One study followed adults who had read a flyer from the Center for Disease Control on facts about the flu vaccine - three days later, older adults remembered 40% of the myths as factual. To make matters worse, they thought the CDC was the source of their information. (Younger adults did better, but not that much better.) Other studies found that repetition, regardless of the source, makes people remember statements as true... and that people forget the not part of a statement after time.

So when I say "the mantle is not a liquid," that might make students remember that the mantle is liquid - and they might someday cite me as their source.

So... what's a teacher to do? Students will try to fit new knowledge into their preconceptions, even when the preconceptions are wrong. So it seems that de-bunking is necessary, especially for some fundamental ideas (geologic time, for instance). But is there any way to deal with misconceptions that doesn't reinforce them?

- Do students remember things better when they've figured them out for themselves? (Does the amount of time spent puzzling make a difference? Are projects that take up a large part of the semester more effective than a hands-on experiment during lecture? And what happens when the fundamental concepts are hard to directly observe, or when the evidence (such as S-waves traveling through the mantle) is difficult to understand?)

- Does it help to use lots of different senses/ways of learning about something? (Does it help to both hear and read, or to hear and read and see and do? Does it help to have touched a sample, or to have played a game, or acted out a process?)

- Is humor effective? Will students remember me snarking about the Giant Amethyst Geode of Death in The Core, for instance? Do students remember mockery? (I would imagine that it's better if I'm mocking someone else - say, Hollywood - rather than mocking a classmate.)

- They say that repetition is effective. So, out of all the way-too-many concepts we cover in Earth Systems Science, what should I repeat? (Geologic processes are slow - I say that many times in many different lectures. I mention certain minerals - quartz, for instance, and calcite - a lot. I've defined "igneous rocks" in about three different lectures already. So I do this a little. But are there other things, important misconceptions, that I should be hammering away at?)

On a related note, I've always told students to study their old quizzes and exams to help figure out what they don't understand. But maybe that's a problem, too - maybe students remember their incorrect answers even more when they use old quizzes to study.

And on another related note - I wonder if this psychological issue is part of the reason why new scientific theories take a while to take hold. (Why are Kuhn's scientific revolutions necessary? Why doesn't science proceed by baby steps?) And is there a lesson for teachers in something like the acceptance of plate tectonics? What was it, exactly, about that American Geophysical Union meeting in 1966 that convinced people? There was supposedly a session on sea-floor spreading that drew a standing-room-only crowd, a session with one talk after another supporting earlier work on magnetism of the ocean floor. Was it the quality of the data, or the volume of the data, or the repetition? Or was everyone at the meeting already prepared to be convinced?

8 comments:

Anonymous said...

So when I say "the mantle is not a liquid," that might make students remember that the mantle is liquid - and they might someday cite me as their source.

The most straight-forward inference from the referenced study is to phrase the correct assertion in the affirmative: "The mantle is solid," and not even mention the alternative. I dunno if that's too simplistic, but it seems to follow.

RBH

jrepka said...

I recall reading a story 10-15 years ago by a journalist who interviewed students who were graduating from Harvard.
He essentially asked them a bunch of "gotcha" questions, one of which was "why does the Earth have seasons?" 3/4 of the responses cited the "fact" that the sun is closer to us in summer.
When I talk to my students about the tilt and the angle of noon sun and day length, I always tell them the Harvard story, capped with "if you can just remember about the relationship between the seasons and axial tilt, you will be smarter than the average Harvard graduate." They all laugh heartily, and when I ask that question on the exam half of them tell me about the sun being closer to us in June.
Last week I made it almost a direct challenge, telling the class that, even after this lecture, most of them would repeat the myth I had just debunked on the mid-term.

Kim said...

I guess the problem with simply using the affirmative statements comes in a couple of different cases. One is when students are very convinced of their misconception, so convinced that they don't actually hear the correct statement. I think students can twist the new statements to fit into their previous understanding. (A liquid mantle, for instance, or groundwater as underground rivers.)

The second problem comes when the concept is a bit weird to understand. The mantle sure doesn't behave like students expect a solid to behave. And in future lectures, we're going to be talking about plates moving and solid mantle rising until it melts and things like that, so it's only going to get more confusing. Students think the mantle is liquid because they've heard about plate tectonics and convection, and because the textbook makes a big deal of it. So it acts like a liquid, at least from their experience... but it isn't. So I think that, at least in the case of the mantle, I need to acknowledge that it's weird and confusing, and then talk about Silly Putty and chocolate bars and other things that can deform when they're still solid, and hope that the point gets across.

There are some situations where I deliberately ignore expected misconceptions. For instance, I simply tell students that the Earth is around 4.6 billion years old, and tell them why we think that, and don't address the possibility that some of the students have been taught that the Earth is 6000 years old. But that's a different situation - I don't want to spread the belief that there's any uncertainty about it.

Kim said...

jrepka -

I get those same misconceptions about the Earth being closer to the sun in the summer.

A year studying abroad in the Southern Hemisphere might take care of that one, but most of my students can't afford an experience like that.

I wonder if there's any kind of activity that could be done on the web, looking at weather in Australia, or maybe trying to figure out why hurricane/typhoon/tropical cyclone season is different in different parts of the world?

magma said...

Want some experience fresh from the undergraduate grinder? I can't answer for everyone, but I can certainly answer for myself!

Do students remember things better when they've figured them out for themselves?
Absolutely. In fact, I'm not sure that I remember anything I haven't worked out for myself.

Does the amount of time spent puzzling make a difference?
To a degree, yes. If stumped, I may (depending on time, interest, and necessity) dig further into it and try to understand. But half the time either the answer is not forthcoming and I have to give up (I've learnt that going to journal articles for answers often leads to only a thousand more questions). If I do end up figuring it out after a long period of puzzling, it may stay with me firmly. This works more with things like maths - if I puzzle out the method to answer a question at great length, it stays with me. With concepts, I'm not so sure. Puzzling over them sometimes only confuses me more - having someone who understands it already and can explain it is invaluable.

Are projects that take up a large part of the semester more effective than a hands-on experiment during lecture?
Not if it's conceptual. It really helps when fundamental concepts are covered firmly in class - I can usually apply them to a project on my own. In most subjects I've done, there have been various trade-offs between the two, tending towards too much application and too little concept teaching.

And what happens when the fundamental concepts are hard to directly observe, or when the evidence (such as S-waves traveling through the mantle) is difficult to understand?
We struggle! :)

Does it help to use lots of different senses/ways of learning about something?
It does, but I've watched far too many videos that were a waste of time over the last few years! Also: more diagrams and more working through things on the board instead of throwing up slide after slide on Powerpoint. I learn SO MUCH BETTER if I have to physically write down notes during lectures. Can't emphasise it enough! I really wish more lecturers would use the white/black boards more to work through concepts.

Does it help to both hear and read, or to hear and read and see and do? Does it help to have touched a sample, or to have played a game, or acted out a process?
Yes yes yes. I would love to have been able to see and handle a chunk of every rock type I've ever learnt about. And I think things are different overseas, but there's nothing more irritating as a student than being asked to identify minerals in the field when you've *never* seen them before in the lab or the field.

Is humor effective? Will students remember me snarking about the Giant Amethyst Geode of Death in The Core, for instance?
Well, I remember The Core being mocked when I was in first year, but I can't remember anything else about that lecture! But then, I never thought the mantle was liquid so...

out of all the way-too-many concepts we cover in Earth Systems Science, what should I repeat?
A bit off the misconception theme, but a real problem I've encountered is over-repetition. Lecturers understandably have themes they revolve around and come back to incessantly at all levels (first year through third year), but sometimes the repetition occurs at the expense of learning the details. Having said that, I don't doubt the only way some other students learn is having the same themes hammered over and over again. So, fair enough.

And an additional thing: continuous assessment through the term/semester is a great idea. It's hard to adapt to as a student, especially if you're not used to it, but I wish it was the norm and exams were scrapped forever. Too often when I'm strapped for time I've thought, "Not to worry about this homework [worth say 5%], I'll ace the exam/massive assignment instead [worth 50+%]". Continuous work throughout the semester forces me to work and understand continuously. And as a post on Scienceblogs confirmed recently: after a week, people don't remember material they've crammed for an exam. And let's face it: most students cram!

magma said...

PS: As for big misconceptions, in the first lecture of first year biology here, they literally said (yelled): "Evolution is a fact. If you think it didn't happen, don't bother doing this course!"

It was quite resolute, and I was most impressed. I suspect half the class was wondering what he was so upset about though! Creationism has a (very) low profile in Australia.

Kim said...

magma -

Very good points. You raise a lot of questions that I also have about getting explanations versus figuring stuff out for yourself. (I tell students a lot of stuff, but then have little hands-on exercises in class for things that tend to be confusing.)

And I'm glad to hear someone speak out against Powerpoint! I use it as a slide projector - I use it from time to time to show pictures that I can't draw. (Maps of the world, photos, diagrams that I can't draw very well.) I don't use Powerpoint lectures, though - I mostly use the chalkboard. Powerpoint lets me talk too fast. And I remember dozing off during a lot of slide lectures, so I prefer to keep the lights on in class whenever possible. And I like to be able to stop and answer spontaneous questions, and it's hard to get back on track in a Powerpoint lecture.

(I know people who use Powerpoint very well, who use the images as the basis for class discussions. But I personally like chalk.)

Bruce said...

Thank you for a thoughtful approach to the mythic question. I teach middle school, after years in high school, and the difficulties are not with the age group, but with the way people process thought. Magma's commentary is perfect, and right in line with my experience. Thank you!!