How common is it for parents to observe lessons in your school? Is there just one "Open Doors Day" or does it go on for longer in your current school? Maybe a week? Or two weeks? On the whole, do you think that this is a good thing or not? A friend of mine who is a Science teacher in the UK says that it never happens in his school and he cannot imagine it ever happening anywhere in the UK. But maybe he is mistaken, both in the UK and in international schools.