I’ve got a new podcast posted, this one with my esteemed colleague Valerie Otero of the University of Colorado at Boulder.  She tells us why she thinks that the idea of student “misconceptions” is very dangerous — and gives us a new way to think about student ideas in the classroom, and some activities to address them.  This is in the Beyond Penguins and Polar Bears episode on Keeping Warm, and targets common student ideas about heat.  Still, the general message about misconceptions is, I think, one that every teacher should hear.

Listen to Warm Blankets and Cold Breezes (10 minutes)

You can also read this month’s content article on heat (what is it?  How do people and animals keep warm?) written by moi.

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Below I am reposting a rather long piece taken verbatim from the website of Steve Detweiler who just says that it’s an “amusing anecdote from a friend of mine.”  So, I’m not sure of the veracity of the story, and some claim that it’s an urban legend.  It may well be.  But it opened up some deep discussion on the PHYSLRNR email list, which I attempt to summarize below.

HEAVY BOOTS

About 6-7 years ago, I was in a philosophy class at the University of Wisconsin, Madison (good science/engineering school) and the teaching assistant was explaining Descartes.

He was trying to show how things don’t always happen the way we think they will and explained that, while a pen always falls when you drop it on Earth, it would just float away if you let go of it on the Moon. My jaw dropped a little. I blurted “What?!” Looking around the room, I saw that only my friend Mark and one other student looked confused by the TA’s statement. The other 17 people just looked at me like “What’s your problem?” “But a pen would fall if you dropped it on the Moon, just more slowly.” I protested.

“No it wouldn’t.” the TA explained calmly, “because you’re too far away from the Earth’s gravity.” Think. Think. Aha! “You saw the APOLLO astronauts walking around on the Moon, didn’t you?”

I countered, “why didn’t they float away?”

“Because they were wearing heavy boots.” he responded, as if this made perfect sense (remember, this is a Philosophy TA who’s had plenty of logic classes). By then I realized that we were each living in totally different worlds, and did not speak each others language, so I gave up.

As we left the room, my friend Mark was raging. “My God! How can all those people be so stupid?” I tried to be understanding. “Mark, they knew this stuff at one time, but it’s not part of their basic view of the world, so they’ve forgotten it. Most people could probably make the same mistake.”

To prove my point, we went back to our dorm room and began randomly selecting names from the campus phone book. We called about 30 people and asked each this question:

1. If you’re standing on the Moon holding a pen, and you let go, will it
a) float away,
b) float where it is,
or c) fall to the ground?

About 47 percent got this question correct. Of the ones who got it wrong, we asked the obvious follow-up question:

2. You’ve seen films of the APOLLO astronauts walking around on the Moon, why didn’t they fall off?

About 20 percent of the people changed their answer to the first question when they heard this one! But the most amazing part was that about half of them confidently answered, “Because they were wearing heavy boots.”

MORE ON THE BURNING QUESTION OF HEAVY BOOTS

I decided to settle this question once and for all. Therefore, I put two multiple choice questions on my Physics 111 test, after the study of elementary mechanics and gravity.

13. If you are standing on the Moon, and holding a rock, and you let it go, it will:
(a) float away
(b) float where it is
(c) move sideways
(d) fall to the ground
(e) none of the above

25. When the Apollo astronauts were on the Moon, they did not fall off because:
(a) the Earth’s gravity extends to the Moon
(b) the Moon has gravity
(c) they wore heavy boots
(d) they had safety ropes
(e) they had spiked shoes

The response showed some interesting patterns! The first question was generally of average difficulty, compared with the rest of the test: 57% got it right. The second question was easier: 73% got it right. So, we need more research to explain the people who got #25 right but did not get #13 right!

The second interesting point is that these questions proved to be excellent discriminators: that is, success on these two questions proved to be an extremely good predictor of overall success on the test. On the first question, 92% of those in the upper quarter of the test score got it right; only 20% of those in the bottom quarter did. They generally chose answers (a) or (b). On the second question, 97% in the upper quarter got it right and 33% in the lower quarter did. The big popular choice of this group was (c)…33% chose heavy boots, followed closely by safety ropes at 27%.

A telling comment on the issue of fairness in teaching elementary physics: Two students asked if I was going to continue asking them about things they had never studied in the class.

———————————

First off, here’s the physics.  Earth is not the only thing with gravity.  The moon exerts a gravitational force on things, but it just exerts less force, mostly because it’s just got less stuff.  Stuff attracts stuff, and so less stuff will attract other stuff less strongly.  If you drop a pen, it will fall slowly, because the acceleration due to gravity is weaker.  Earth is far away, but that doesn’t really matter — when you are on the surface of the moon, the gravitational attraction of the moon is stronger than that of the earth.  That’s why the astronauts could jump very high on the moon.  You would weigh less on the moon than you do on the earth.  If the astronauts jumped really really really hard, they could float away from the moon.  The same is true on the earth (but to jump that hard, you need rockets, and that’s what the space shuttle does).

So, here’s the discussion.  One instructor said that she had used similar questions in her class, and gotten similar results.  Many students thought the pen would float away.  One year, she asked them instead about a crescent wrench instead of the “apocryphal pen.”  They all answered that question correctly!  Another instructor, however, gave a similar set of questions to his class, and most of them answered correctly.  What’s he doing differently?

What’s the problem?  This question forces students to challenge a preconception that they had walking in the door — perhaps that “things float in space” or “heavy things get weighed down.”  Apparently the misconception that the moon has no gravitational attraction persists through most physics courses.  Even though they might be able to state that the moon has gravity (as evidenced by correct answering of the second question, as to why the astronauts stayed on the moon), they have trouble transferring that understanding to the “what happens when you drop a pen on the moon” question.  They are thinking, argued one instructor, in terms of the surface features of the problem (we’re on the moon!) rather than the underlying features (all chunks of matter have gravity).  Students transfer more when they’re interactively engaged in the material, says the research (e.g., Cognitive Development, 6, 449-468 (1991), Learning and Transfer: Instructional Conditions and Conceptual Change, Michelle Perry).

John Clement gave a few ideas for ways to address this misconception in class:

Given enough time you could propose a number of what-if questions which might help the TA understand what is going on.  Why did the rocket have to fire its engines to prevent a crash?  Why don’t rocks fly away from the moon?  What force pulled Apollo 13 around the Moon?  Whey when the astronaut dropped a feather and hammer did they both fall to the surface of the Moon? This last one has no heavy boots!!!

Another really important question is to ask why they think there is no gravitational attraction on the Moon.  A number of students will reply “because there is no air”.  The common misconception is think that “gravity” is due to the air pressing you down.  Or they may say because the Moon does not rotate, as this is another common misconception.  These are explained in the teachers manual for Minds on Physics, and students are asked questions
to bring out these misconceptions while building a coherent model of gravitational attraction.

So rather than attacking the “heavy boots” conception, the student has to internalize the model that there is (at least in classical mechanics) no threshold to the action of forces, and that unbalanced forces cause acceleration.  Then they have to apply it to a variety of cases, of course, along the way.  It helps to have them apply these conceptions to objects on other planets.  So blocks of wood in a water filled bowl all float at the same level on the Moon and the Earth, but springs supporting masses are stretched less on the Moon.

So the “heavy boots” is not the primary concern.  The concept of forces and acceleration are the primary concern.  Once the students have a firm model of forces, and of NTNs general gravitational law, the idea that things can float on the Moon will go away.

A few more comments that I liked:

Can the boots be heavy if the astronaut is not?  Are the boots heavier than the astronaut?  If not, do the boots weigh down the astronaut or does the astronaut way down the boots?  I think a few questions like this can make the logical inconsistency evident. (Jerry Touger)

But, countered Dave Van Domelen:

Actually, it goes along with ideas like blankets being intrinsically warm.  Qualities as properties of things, rather than the result of interactions.

And from John Clement, an idea I’d never heard before:

This comes from the concept that “gravity” exhibits a threshold effect.  You have to have enough of it to be pulled down, otherwise you float.

Which, pointed out a discussant, suggests that students are using buoyancy as an analogy — if you’re heavy enough you sink, if you’re light enough you float.  Or, perhaps, friction is the correct model — there is a threshold at which the force becomes effective.

Of course, trying to address these misconceptions as “problems” to be plucked out of the students minds won’t work.  They’re using these ideas because they fit with their experience of the world.  Trying to understand their underlying conceptions (without perjoratively labeling them as misconceptions) and working from there, will be most productive.  Dewey Dykstra has written quite a bit about this, and you can see my previous post on that.

Other resources:

• Minds on Physics (vol 4) has a good section on moon/earth comparisons
• An entire thesis was written on the “heavy boots” problem
• Chapter 4 (p 44-46) of another thesis also deals with this problem
• David Hammer, More Than Misconceptions” published in AJP in 1996.

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Firstly, I just have to say how beautiful the view is outside the airplane window right now.  It’s been an extraordinarily bumpy ride on my trip from San Francisco back to Denver, and I’m a real nail-biter when it comes to turbulence.  But now we are above the clouds and the sky is white with a band of blue and purple at the horizon.  I’m thinking of light scattering and optics and it’s quite soothing.

But on to the meat of today’s post.    There are a lot of ways you can slice the essential “messages” of education research, and what we know about how people learn.  My colleague, Noah Finkelstein, slices it this way:

1 – Actively engaging students in learning is important
2 – What people already know affects what they learn
3 – Context shapes what students learn
4 – Teaching is an effective way to learn

I’m reading a paper right now that focuses on number 2 – learning depends on what people already know.  There is a whole body of thought (that’s quite well substantiated by research) that learning isn’t just the addition of new bits of information, but rather the process of changing people’s existing conceptions.  In that way, it’s important to know where you’re starting (what people’s naïve conceptions are) so that you can CHANGE them, rather than just trying to overwrite them.  People have their existing ideas for a reason – they make sense, and they have some predictive power.  So the new idea has to provide some advantage over the old idea in order for people to drop their old model.  The same content might make perfect sense to one student, who doesn’t have a previous conception that conflicts with it, and yet be actively resisted by another student. The job of a teacher can be quite difficult, then!  As if you, dear reader, didn’t know that already.

This is old work, from Posner in 1982.  But realize, there is some debate as to how well-formed these ideas are.  As this paper by Hewson argues,

because students have experienced and thought about the world, they do come to class with ideas, often hazy, ill-formed and inappropriate, but ideas nonetheless.

There’s some evidence that people don’t come to the table with well-formed “theories” of how the world works, but rather these sort of muddy “proto-ideas” which often shift depending on the context of the problem in question.

But anyway.  An example of a misconception is that “mass / weight = “heaviness”” or that some objects have mass and others (like air or hair) do not).  Scientifically, of course, all objects have mass, and mass is a measure of the amount of matter in an object.  So, how can we work with those naïve ideas to help students arrive at the scientific understanding of mass (or density or anything else)?

The paper that I’m reading right now (Hewson and Hewson, J. of Research in Science Teaching, vol 40, p. S86, 2003) proposes four main ways that teachers can teach in a way that uses students prior knowledge.

1.    INTEGRATE new conceptions with existing (presumably correct) conceptions
2.    DIFFERENTIATE existing conceptions into more fine-grained categories or bins.  This assumes that the student is applying a concept too broadly, and they can see that what was plausible in one situation is not plausible in a different, more complex situation.  (For example, “heaviness” is an undifferentiated concept which includes mass and weight).
3.    EXCHANGE one conception (presumably incorrect) for a new one.  The new concept has to be shown to be more useful and predictive than the old one for the student to become dissatisfied and toss their old model.
4.    CONCEPTUALLY BRIDGE the new idea with meaningful common experiences, to give the student a context for seeing why the new idea is plausible.

In this study, they wanted to see how these different techniques affected student understanding of density.  In the control condition, they presented the main ideas in density and floating (eg., density = mass/volume, all matter has mass), discussed them, and did experiments to demonstrate these ideas.  Pretty typical science class stuff.

In the other class, they took what they knew about students prior knowledge (eg., mass and volume of an object affects whether it sinks, density = “crowdedness”), and geared their discussion based off those ideas, arriving at the more scientifically valid ideas (density = mass/volume, density is the packing and mass of particles, all matter has mass and density).

They found that starting from the alternative conceptions was more effective in teaching students the ideas they wanted them to learn (as measured by a conceptual quiz), though it wasn’t as good as one would have hoped.  But still, better than the standard “tell them what you want them to know” approach.  But both groups still held on to their alternative/naïve conceptions that they started with, at least to some degree.

Hewson & Hewson, J. Research in Science Teaching (40) PP. S86–S98(2003)

So, the take-home message is, starting with students’ existing ideas may be more effective than the standard textbook approach of presenting the ideas that you want them to learn.

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[Session:  Eugenia Etkina - Pedagogical Content Knowledge (PCK)]

What you believe about how people learn, and about the role of teachers and students is in the classroom, WILL affect your teaching.

For example, do you believe that a student misconception is something that needs to be eradicated with a clear example that clears up the misunderstanding?  Or do you think that the misconception will always be there?  What you believe will affect how you teach.

Take for example the idea that horizontal and vertical motion are independent.

Here’s one way to teach this.
Predict and explain

Show students an apparatus that can drop a ball down and shoot another horizontally. Ask your student

Projectile apparatus

s to predict what will happen if a ball is shot horizontally and dropped straight down.  Most (if they haven’t seen this befre) will predict that the one dropped straight down will hit the ground first.  Show them the experiment, or a video, of a ball that drops vertically and one that is thrown horizontally. They will, in fact, hit the ground at the same time.  But you’ll find that students will debate this.  Because they have a certain expectation, this actually affects their perception – they literally hear the balls hitting at different times.  You can slow down the video and see that they do hit at different times.  But, studies have shown, they’ll find ways to rationalize this, like “air resistance” so that what they see stil fits within their understanding.  The misconception is really robust.

So, here’s another way to teach this.
Observe and explain — then predict

Cart and ball video

Show a video of a cart that is moving horizontally.  It throws a ball up which rises in an arc and falls back into the cart.  What do they see?  It falls back in the cart.  There’s no arguing against that.  Some students will think that there must be a magnet bringing the ball back (though you can show that it’s a wooden ball).  Others will notice that the ball continues moving horizontally while it’s moving up and down – it’s keeping pace with the cart.  Great!  That’s what we want them to notice.  You can then show them a woman on roller skates, throwing a basketball straight up. She catches the basketball and it’s easier to see that there’s no magnetism involved, and you can see the mechanism

Eugenia on rollerblades

of the throwing (her hands move straight up).  Great, so now we have the idea that horizontal and vertical motion are independent.  NOW go to the first video, where the ball drops and is thrown horizontally.  Ask them to use the idea they just learned to predict what will happen!  Not their intuition.  As scientists, we use ideas to predict, not intuition.  If they use the new idea – that horizontal and vertical motion is independent – they’ll give the correct prediction (that they will hit the ground simultaneously.  Their job now is to figure out why their intuition brought them to the wrong place.  There is something in that idea that is useful, just not in this situation (some might call it a phenomenological primitive, or p-prim).

But it’s best to address that misconception after the new idea has been created.  If you show them the experiment that flies in the face of that misconception – first – they may not see or believe what it is that you want them to.  This sort of full-frontal “force students to abandon their wrong ideas” isn’t effective.  The almost sneaker, back-door kind of approach to show them first what is, create a new idea, and then apply that idea to a situation which they may have naively predicted the wrong behavior, seems to be more effective.

Go to the ISLE website for these videos.  Here is the direct link to the videos.

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I’ve got a new podcast series out, and this one is my best yet.  I’ve been hired by the wonderful folks at the National Science Digital Library (they provide a central depot for great digital media for teaching science) to create a podcast for elementary educators on using polar science in their teaching.  We (me and my co-conspirator, the multi-talented Robert Payo) focus on misconceptions and myths about science and how to address them with science from the poles. This is part of the Beyond Penguins and Polar Bears webzine.

Visit the Beyond Penguins and Polar Bears Podcast!

So far we’ve done a show about the geology and volcanoes of the poles (and an Earthwalk with my old colleague Eric Muller of the Exploratorium), another one on ancient polar mammals, and the most recent (my favorite so far) on birds of the poles and how to use birdwatching to do real science.  These are all pretty short, 10-15 minutes. Here’s a direct link to the birds episode. I enjoyed this one in particular because I got to play so much with ambient sound and creating soundscapes, and my friend Tom has the *cutest* 10-year old neighbor who can deliver a script like nobody’s business.  Fun, fun storytelling.  And Jennifer Fee is awesome.  (And she’d read sciencegeekgirl before I called her up for the piece!)

To find out more and listen to the Birds episode, go here!

To go to the iTunes U site with all NSDL podcasts go here.

To see all my podcast series, go here.

I am a science education and communications consultant -- view my website for my full range of services.

Especially for K-12 teachers, check this baby out.  The National Science Digital Library has Science Literacy Maps online.  For a bunch of different topics (Math, Technology, Physics, Nature of Science) you can click to get a concept map of a set of topics.  In physics, for example, you can click on waves to see a map of all the concepts related to waves.  Even better – there is a link within each section to see a list of student misconceptions (with references) related to those topics.

I am a science education and communications consultant -- view my website for my full range of services.

I’ve just posted a new episode of my Science Teaching Tips podcast — Which is Closest?

Which is farthest away from the earth, the stars or Pluto? The answer may be obvious to you, but a lot of people get this wrong.  Here’s the task — arrange these in the order from closest to furthest from the earth:  moon, sun, Pluto, stars, and clouds.  Think about it first, and then listen… listen carefully!  It can be easy to miss the mistakes that people make.

We went out and harassed the employees at the Exploratorium with this little survey.  I was astounded by what we found.  Many teachers are.  Linda explains why people (even highly educated people!) answer as they do, and what this means for teaching about science.

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I’ve posted a new episode of my Science Teaching Tips podcast: Private theories. TI Director Linda Shore was one of the people originally involved in the Private Universe video (from Annenburg Media), which showed surprisingly persistent misconceptions in students. In the famous opening scene, they interview students as they graduate from Harvard and ask them why there are seasons. Almost all of them said that it’s because the earth gets closer to the sun during 1/2 of its orbit, despite the fact that this doesn’t explain why the southern hemisphere has summer while the northern hemisphere has winter. [The real answer is that the planet is tipped on its axis, so 1/2 of it is closer to the sun during part of the year].

In this podcast, Linda Shore explains how she probes student thinking to find out about their private theories about the universe. Without understanding what students are thinking, it’s very difficult to help them form new conceptions of the world.

I am a science education and communications consultant -- view my website for my full range of services.