We always pull them out during the school year. My daughter will be going into 2nd grade and my son will be in Preschool. We notify the teacher months in advance and remind her often. I would say about 75% of her class last year were taken out for a family vacation to Disney World. Also, where we're from, vacation absenses are counted as regular absenses but their not counted toward an amount of missing time to fail. But, my children are young. When they get to the older grades and high school then that may be a different story. When my daughter was in 1st grade, she had enough homework to work on that took up time on the flight to and from WDW. Plus, I see it as a good time to be sitting still with your child looking at her work as she is doing it and being able to review. You've got so much time on that flight to use the time constructively.