I subbed today for a sixth grade teacher. This school has 6th grade in the elementary.
This was probably one of the wost classes I've subbed for in a long time.
It turns out that I had NOT read all of the Diary of a Whimpy Kid books. I started Dog Days today. With any luck I'll be able to finish it before the end of the year.
When a 6th graders asks you, "why do the veins in my wrist look blue?" don't bother explaining to her that it has more to do with which light wavelengths your skin can not absorb than it does with how much oxygen the blood is carrying. Expect that their science teacher will have explained the latter theory to them. Also expect them to think that you're wrong, soley on the basis that you're not a "real teacher."
Try not to worry about what other incorrect information they're learning.