I agree with the other posters who say go straight into the Swiss system.

It is not the purpose or aim of the International Schools to provide any sort of transition to the Swiss system. They are largely self contained and putting your kids there won't facilitate a transition but merely postpone it. They are ideal for exapts who are here for maybe 1 to 3 years and hence don't see the need to adapt to the local system. From what I've heard the quality of teaching the local language is pretty poor in International Schools. Kids are encouraged to associated with one another and not with locals and many are quite helpless when they have to fend for themselves outside of this environment. Besides which, many of these schools are very expensive. Swiss schools are free.

Whereas many parents in the UK put their kids into private schooling because they believe that this is where they will get the best education and get the best learning environment, the same cannot be said of Switzerland. Most private schools (I'm not talking about the International Schools here) pick up the kids that for some reason are failing in the state system. Such schools and their pupils thus have the stigma of rich parents trying to help failing kids by throwing money at them. Before volunatrily considering sending your kids to such a school, you should ask yourself if this is the message you want to put out and the stigma you want to place on your kids.