DS is only in Kindergarten, so not too big of a deal...
At the beginning of the school year I simply wrote a memo to his teacher, cc: to the office. Something like this...
_______________________________________________
This letter is to let you know that my son will not be at school beginning on Friday September 19th thru the following Friday, September the 26th.
I will be happy to see that he completes any make-up work before he returns on the 29th
Sincerely,
________________________________________________
Sure, his teacher and the school may probably find out from him where he is going... (which his teacher did) But, IMHO I do not have to offer any information. And, I do not need to ask the schools or the teachers permission to make these plans for my family. I simply did not even 'go there'!