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Do you take your kids out of school for vacations?
We did it once when my kids were in Kindergarten and 2nd grade and it worked out ok even though it is frowned upon by the schools. Now that they are in older grades I don't think it's worth it for the amount of school work missed. Some teachers are more accommodating than others but I've heard it can be really hard to catch up on everything after missing a significant number of days. Now, if it's just a matter of missing a day to take advantage of cheaper flights than I could see the advantage, but not a whole week or more.