Teaching Misconceptions

Teaching new things to young people is quite a difficult task. You need to somehow engage them, while introducing them to concepts they may have had no idea about before hand or even care about now!

During my limited years as a teacher (5+) I have noticed that many teachers often have just as many misplaced conceptions as the people they are trying to teach! Before I continue I will quite honestly say I have also done it. The most recent one for me was telling children about pressure and ice skating.

I was teaching my class about pressure and how an ice skater exerts a very large pressure on the ice due to the very small area of his/her blade. This part is all correct (I hope!) but I then went on to say that the reason an ice skater is able to glide across the ice is due to this very high pressure, melting the surface of the ice and reducing the friction!

This makes perfect sense to me, and scientifically seemed quite sound. Unfortunately I have recently learnt this is almost certainly not true as the pressure exerted by an ice skater is probably somewhere in the region of 12 atmospheres and that is not high enough to melt the ice more than a few tenths of a degree.

Now this seems such a simple mistake but something like this will then travel with that pupil throughout their lives (well if they were listening in the first place), and may never be corrected. Does it matter? Well to be honest probably not in this case, but this is only one isolated example.

I have seen some really shocking statements since I started teaching, the worse probably being from a head of science at my first training school. When discussing the heart and how it pumps blood around the body she drew a very nice diagram (figure of 8) showing how de-oxygenated blood is pumped to the lungs to pick up oxygen, and how oxygenated blood was pumped around the body. Though simple, this is a very effective diagram and I have used it in my lessons as well. The oxygenated blood is coloured in red to show it has oxygen and the de-oxygenated blood is shown as blue to show the lack of oxygen. She then proceeded to tell the children how if you look at your wrists, you will notice how it is blue, this is because it is a vein and it carries de-oxygenated blood!

I was shocked that someone who has been teaching for such a long time, and was head of department could carry such an incredible misconception. At best de-oxygenated blood is a dull red or maroon colour, it is never, and will never be blue. The blue colour of the vein is due to absorption of light by the skin and blood, and how blue does not really absorb very well in skin, so a deep vessel will appear red, where as shallow vessels will appear red (I have kept this explanation vague so as not to detract from the point of the article!)

Fortunately the teacher in question was more than happy to be corrected on the matter, and I assume she no longer teaches this (I hope). The real question is how costly could that mistake be to someone. Perhaps a bright student takes that piece of information all the way through to a medical interview where they happen to mention it!? I know it's unlikely but it is a possibility, and a scary one at that.

I don't think there is any answers to the problem, and we will all make mistakes, especially when teaching subjects that are not our specialism, but perhaps more care should be taken to check the "facts"? More planning time for teachers would be a good start!