Record some students speaking a little simple French and then a little English (if they can) - or even better, video it.Things like, have they got a pet, brothers and sisters, what is their house like, what is their personality like, what are their favourite sport, etc. Photocopy a timetable, take back an old French exercise book. Perhaps a numeracy worksheet? See if your pupils can work out what to do. Record them singing a nursery rhyme etc. Do a little survey in the class about which country pupils have visited and get your own kids to compare it. It sounds like you have lots of ideas already, so I'm sure you'll really enjoy the experience. Don't forget to take some photos of your own school with you - particularly the uniform, as it's really intriguing for people over there!