i went to disney world the first week in nov. so i missed a weeks worth of classes. when i told my professors they just asked if they could fit in my luggage. they told me not to worry about getting stuff in ahead of time, but it would be better if i could, but still not a big deal. actually one of my professors pushed back a test so i wouldn't have to miss that. depending on your professors, they should be just fine. just explain that you are going on a family vacation and everything SHOULD be fine. have fun!!