When I was a little boy, I used to think our blood
was blue. I thought this because in our science
books at school, they showed human anatomical
diagrams of the red blood flowing directly from the from the lungs and heart, then passing through the arteries and the capillaries
then suddenly turning blue, going up through the veins and back to the lungs and heart again. I assumed that half of the blood in our body was blue at any given time, and the only reason why we never see blue blood
when we cut ourselves is because blue blood instantly turns red when exposed to oxygen
Of course, this isn't true, it's just the thinking of a child that didn't understand that the blue blood in the diagram wasn't really blue, it was a representation of lack of oxygen in the blood. This was further visually supported by looking at somebody's varicose veins, which are blue. I eventually was corrected by a science teacher, which is fortunate because I would have made a real fool of myself had I said this in public.
I'm amazed how many people still believe this! After discussing this topic with some of my friends, I noticed that they, too, had made these assumptions and went on with their lives, not noticing that they were miseducated. Maybe it's time for our educational curriculum to make this distinction in science classes, or better yet, it's time for the blue/red blood diagram system to be done away with. Not that it matters a lot, after all unless the student is going into medicine, they'll never be in a situation where they'll know that blood isn't blue. Now if you'll excuse me, I need to turn these pop can tabs in for a kidney transplant.