Do you still believe blood is blue ?

I bet a lot of people said this, but I'll say it anyway. My teacher taught me blood was blue until it hit air.

I didn't argue the point cause I was so young, but I was pretty sure she was wrong.
To anyone who still believes blood is blue until it gets oxygenated from air: Do you even know what blood does? Why it goes into our lungs? Specifically to get oxygenated. Blood carries oxygen throughout our bodies, ergo, contact with air just means you're bleeding. Our veins look bluish/greenish for other reasons.