I agree with the other posters. Just send each teacher an email. No need to go into specifics about what the child will be learning. As a former teacher, I would read the first line about when they will be gone and that's it. Don't over do it!
Also, have you read your school handbook regarding homework or class work? The school I used to teach at had a policy that all work would be completed upon return. It is very difficult, especially this early in the school year, to say what will be covered in a week. Many teachers will be reviewing concepts to see where a students strengths and weaknesses lie. When does your school year start or has it started? We don't start here until Sept, 9th.
If I had a student that requested work prior to a vacation, I would remind them of the policy and tell them to write a journal or make a presentation upon returning. If they were working on a unit in a book I would tell them to continue in the unit or if they were reading a novel, ask them to continue reading to a certain point.
When we took DD 1 out for a few days last October she completed a project on the countries of Epcot. She also received a folder of work upon returning that she missed and that was completed over the weekend following her return.