We all know that the best way to boost the linguistic progress of students is to get them in an immersion situation for as long as possible. At Ripon Grammar we could measure the improvements in listening and oral skills made by those who did the exchange.
Teachers are always striving to increase motivation and skill in all sorts of ways: games, using new technologies, looking for new ways to practise grammar and vocabulary. However, I would suggest the best single thing we could do, if an immersion stay abroad is impossible, is to organise an immersion period in school.
How could this work?
You could first persuade your senior leadership that the benefits would be worthwhile - improved results, higher motivation, personal and intercultural benefits, higher take-up for A-level. You could even present the equal opportunities case, as there are always pupils who are unable to do exchange visits.
You could request a week, probably after exams in the summer term when teachers of other subjects may be less protective of their time. You could ask for volunteers from your Y10 and AS students to join in. Maybe about 30 would be a good number. It's likely you would attract your most motivated linguists. That's fine, but don't make it exclusive.
You would then take them off timetable for a whole week and design a programme of activities with the emphasis on enjoyment and maximum "comprehensible input (i.e. target language). You might include a smattering of grammar, but keep that to a minimum. Remember that immersion is attempting to recreate the conditions of natural acquisition. You would be quite strict about using the target language for everything, even including lunch. It should be possible for pupils to dine together with staff using French.
You would include your languages team, an assistant if you have one and any native speaker visitors you can get hold of. Maybe you could invite a play group. Perhaps you could include a suitable film with some guided activity. You could include song, "serious" work on written texts and listening skills, time in the computer room doing interactive tasks and maybe some major creative task to complete during the week e.g. a playlet, a magazine, a song.
You could have a mini French party at the end of the week to celebrate achievement.
Now, is this all feasible? With smart planning for teacher cover during what might be the "gained time" part of the year, I think it could be. Not every MFL teacher would be involved all the time. For teachers in England it could even be a development opportunity included as a performance management objective. It would be a great way to build a teamwork ethos in the department too.