In my state, we are allowed a certain number of unexcused absences before things start getting reviewed. An excused absence is an illness with a doctor's note, funeral, even a college visit(though they are limited to 3 a year I think). My son was in the hospital for a week during the school year and it was all excused because obviously it was something that was medically necessary. Any other absence is unexcused . It could be that your sick or that you went on vacation. As long as you don't go over the days , your ok. They don't like people taking their kid out during the school year for vacation, but it's the parents choice . If our schools go over their "allowed"absences, they miss out on some of their funding . So they have really cracked down on it. During the end of the school year when your in for a half a day doing nothing but watching finding nemo, the school sent out letters basically begging for parents to make sure their child attends school. They were approaching there limit.
This is another thing that I always hated as a student. If this day of "learning" is so unimportant that we are going to spend the day watching a movie that would be VERY hard to say is educational (much less then a vacation) or playing video games (in high school I had a week where my teacher who was in grad school had something he wanted to do for school while getting paid so he decided we would all work on "problem solving skills" that week... we played lemmings for the entire class all week.)
How is this stuff ok but students can take time off for a vacation? If every day is so important maybe every day should be spent on something actually educational.