At our school, the children were allowed to take them or any cther hand held devices e.g. dvd player but just for the journey (4 hours)
The teacher then took them off of them for the 3 day residential but then gave them back for the journey home. I think thats reasonable dont you.
BTW - hating the snide comments about teachers being paid for the residential trip - NO THEY ARE NOT! Far from it infact. Residential trips are rewarding but so tiring - you are responsible for 50 + children 24 hours a day. Trust me, teachers pay does not even cover half of what they do, and thats not even considering the hours of risk assessing, budgeting, letter writing, parent meetings, collecting money etc beforehand.