OH and I say no as an ex teacher who has done residentials, albeit with secondary school age. Even then we said no to consoles.
I also say no as a mum to a child who has a DS. I myself have a DS too. School trip not the place IMO.
Yes, on some trips they may not go missing or get damaged but on many occasions they do.
This is not a holiday it is a school education trip.
Even if it were a school holiday trip I'd still say no because of the loss/damage potential.
Oh, and teachers don't need to be engaging children all day and evening on school trips. parents don't need to engage childre 24/7. Children should be able to engage themselves and play with one another, without the use of a games console. If they want time out - read a book or magazine, play a card came, etc.