Biology Misconception
Students believe that the colour of veins is blue. A widely held misconception is that the colour of deoxygenated human blood, the blood returning to the heart and lungs in veins, is blue. This concept of blue blood has been illustrated in text books to distinguish arteries from veins to help students understand the concept. (ENC) Blood is either dark red (venous) or bright red (arterial), but if we were to illustrate this in textx to help teach students they could get mixed up between which blood vessel carries deoxygenated blood and which vessel carries oxygenated blood. As blue and red are complete opposites it's easier for students to understand that veins carry deoxygenated blood to the heart and lungs and arteries carry oxygenated blood away from the heart and lungs.
Another reason this is a widely held misconception is that when you look at the blood vessels in your hands, arms and legs they look blue. Therefore, why don't we bleed blue blood? That has been a question I encountered on my last practical. I was even unaware as to why it was. After that, I found that larger blood vessels that are further away from the skins surface appear to be blue because light is refracted by the skin and the vessel walls.
How to address the misconception
You can ask what colour the veins and arteries are, have a visual of the circulatory system on the board and ask students what is wrong with the picture, explain to students that the reason for colouring veins blue is a technique used to help emphasise that veins carry deoxgenated blood and arteries carry oxygenated blood, ask them if veins are blue why don't we bleed blue blood?, use other examples where refraction changes the colour of something.
ENC-http://www.enc.org/features/focus/archive/misconceptions/document.shtm?input=FOC-003301-answers
Syllabus point
compare the structure of arteries,
capillaries and veins in relation to their
function (9.2.2)
Hi Sam,
ReplyDeleteI can see how this misconception would come about, especially as students who are often at a concrete cognitive level of thinking and require visual simulations or tangible evidence would look at the veins and see the blue colour of their veins would be confronted with a very challenging concept that the blood is not actually blue but red. I like your way of explaining this misconception to the students and I think it would assist their understanding of the misconception.
I think if you started the lesson by asking the students to look at their veins and then ask them what colour their blood is, this would be a great and interesting starting point to not only to teach the lesson around which would capture the interests of the students but would also allow you to gain a quick understanding of who are the more abstract thinkers in the classroom.
Sam, I have to be honest and tell you that I had never thought about this before and therefore will admit that I have had a misconception that has never been brought to light until now. I did not even think as to why the veins are blue, only knowing it was deoxygenated blood, not the refraction. I think it is a great example you have developed and I relate it back to the mirror example that we looked at last semester. Visual stimulations are excellent in the explanation of such misconceptions. I know that I certainly learn better from visual guidance, especially in anatomy, and that it would help in shifting the misconception. I also agree with Simone that this would be a great strat to a lesson that will keep them hooked on the content and maintain them interested. Great example!!!
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