So, I know blood is red but...
When I was at school, on diagrams, the oxygenated blood was coloured in blue to show it was oxygenated and the deoxygenated blood was red. This made sense to me because there's oxygen in water and water's blue.
DH is a science teacher and he's just told me that the diagrams now are the other way around. Oxygenated blood is red and deoxygenated is blue. This makes no sense to me.
Am I imagining that it was the other way around or did they change it?