misconceptions

Knowing the word for something and having an understanding of it are not the same thing

It ain’t what we don’t know that gives us trouble, it’s what we know that ain’t so.”
Will Rogers
 A common failing in all levels of science education is mistaking having a word for a phenomenon with having an understanding of it.

 

To take a very simple example, if I ask any of my students why the apple falls ‘down’ from the tree they will all say ‘because of gravity’.

If I then ask them what ‘gravity’ is I get a lot of mumbled responses before they finally acknowledge that they have to idea.

I don’t either.

Neither did Newton.

Scientists still don’t.

Or I could pose the following:
My book is sitting on the table. There is a force of gravity acting on it pulling it downwards.
The fact that it doesn’t fall downwards must mean that there is another equal force acting upwards.
So, I ask, what is this force?
“That’s easy”, say the troops, “it’s the table.”

But a table isn’t a force, I reply – a table is a table.

It gets better. Let’s assume that the weight of the book is one Newton.
Whatever is acting upwards (opposing the gravitational force) must therefore also be one Newton.
Now if I put a heavier book on the table (two Newtons in weight) the table now needs to push back upwards with an equal force of two Newtons. How come the table ‘knows’ exactly the right amount of force to push up with?

It’s obviously a very clever table.

What happens if it got its sums wrong and pushed up with a force of three Newtons when it should have just pushed with two Newtons?
Hmmm . . .
force-on-a-book
In our Physics and Applied Maths classes we do lots of calculations with this upward force. And because we talk about it so much we gave it a name. It’s called a “reaction” force, signified by the letter R (because we’re nothing if not imaginative).
I use this as an opportunity to predict the future career path of the students in front of me. Engineers are perfectly happy not to know anything about the origin of this reaction force. I just need to get out out of their way while they get on with the business of using it to get the right answer.
The physicist is the guy/gal who knows there is something odd about all this and isn’t happy until they get to the bottom of it.
The dilemma I constantly struggle with is the following: how much time should I spend  trying to unravel students’ misconceptions in order to give them a deeper understanding of the basic concepts when the exam is just looking for superficial answers.

So more and more I put my emphasis on the wonder of the subject. Because that’s what drew me into it in the first place, and then gradually I sorted out some of these issues myself. But I still still struggle with most of them. But it’s a wonderful struggle.

 

So don’t worry if students at any age don’t have a fully-worked out understanding of what’s happening. Once they’re happy to ask questions, and the environment is there to encourage this, everything else will follow in its own good time.

At least that’s what I think.

I could well be in a minority of one . .

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Questioning Science Education

Starting with four basic questions (that you may be surprised to find you can’t answer), Jonathan Drori looks at the gaps in our knowledge — and specifically, what we don’t know about science that we might think we do.

 

So goes the blurb for the one of the latest talks on TED.  Drori asks four basic questions:
1. Where does the “stuff” in trees come from?
2. Can you light a torch bulb with a bulb, battery and a single piece of wire?
3. Why is it hotter in Summer than in Winter?
4. What is the shape of the planets’ orbits?

How many can you answer correctly?

Drori then refers to a couple of videos he was involved in producing a few years ago where graduates of MIT were recorded giving their answers to some of these questions, and surprise surprise, almost all were unable to answer any question correctly. There is a nice moment when one young woman, on finding that she is incapable of puting the electric circuit together, justifies her lack of knowledge by saying “I’m not an electrical engineer, I’m a mechanical engineer”.
Drori wasn’t able to use the clips in his presentation due to a technical hiccup, but I am assuming that these are the videos he is referring to. The first is entitled “Can we believe our eyes?”, while the second is “Lessons from thin air”.

I referred to these videos in a post last year, and mentioned that the answers given by graduates were very similar to those given by six year olds. What I didn’t realise is that, according to Drori, research shows that concepts like Magnetism and Gravity are better understood by children before they go to school than afterwards!

This is stunning, and a little difficult to believe. I would like to find out where he got his information here, but then again, just because it goes against common sense isn’t reason enough to disregard it.

Another question asked in the “Can we believe our eyes?” video goes something like this;
Imagine you are facing a mirror. If you want to see more of your body should you move towards the mirror, away from the mirror, or does it not make any difference?
The point being made here is that ‘hands-on’ experience is not necessarily very educational. They even received incorrect answers from the barbers who work with mirrors every day. It reminded me of the recent fascinating discovery that cattle and wild deer tend to align their bodies in a North-South direction when standing in a field (link). How could we not have noticed that before?

I guess if we are not directly interested in something (almost at an emotional level) then we are rather unlikely to notice or form a deep understanding of it, and the traditional teaching approach of simply repeating the class lesson is of little use in changing that.

I know myself that I learned bugger-all physics in six years of secondary school or four years of college. I did however learn more in one year of teaching Leaving Cert Physics than I did in all the others combined. This was obviously because I was no longer ‘learning’ to pass an exam, but rather I was learning to survive in a classroom where I knew  I would be taking questions from students who were expecting nothing less than an A1 in their Leaving Cert. I had taught in a previous school but had spent too many lessons ‘winging it’ and getting caught out, so for me this was a fresh start and therefore there was certainly an emotional motivation.

Which is why, if I find out that my students know less about magnetism and gravity now than they did before I taught them, I may just have to find a cold, dark room and lock myself in it for a long time.

Chernobyl: the legacy

348910187_58dea72f81_m.jpg

Photo from Jeremy Nicholl on flickr

I have mentioned this before, but it’s worth throwing it up again (and again)

Given the low radiation doses received by most people exposed to the Chernobyl accident, no effects on fertility, numbers of stillbirths, adverse pregnancy outcomes or delivery complications have been demonstrated nor are there expected to be any. A modest but steady increase in reported congenital malformations in both contaminated and uncontaminated areas of Belarus appears related to improved reporting and not to radiation exposure

Source: World Health Organisation

It is a similar story for the survivors of the Hirishimo and Nagaski nuclear explosions.

This is always greeted with (i) disbelief, (ii) scepticism or (iii) amazement (at best) by my senior students.

I guess it’s very to argue with our gut feeling. But this is ultimately why we have this thing called SCIENCE, even if it is warts and all.

Where does the ‘stuff’ in trees come from?

learner.org is an interesting site which “uses media and telecommunications to advance excellent teaching in American schools.”

One of the issues they address is the area of misconceptions in Science.
This is a wonderful video which asks where does the material that makes up trees come from.

College graduates from Harvard and MIT were asked and not one of them gave the correct answer. In fact their answers were very similar to those given by six year olds.

It makes us question what other serious misconceptions we are responsible for, and leads us to question what and why we are teaching.

If we put together the ten most important ideas in science, how many of them are emphasised in our science courses?

College students answering these questions kicks in at about the 8-minute mark.

A primary school kid gets a look at solid air (dry ice) at 53:20. The look on his face is worth waiting for.

The video is 1:21 long. Access it here