I basically don’t, but I have observed a few teachers who do so well (amongst the vast majority who do so badly) and look back on some of my own ways of avoiding it as a waste of time and energy (both the students’ and mine) and so have an open mind about it. Someone has emailed me asking if I’ve written on the subject, and indeed I have:
A well balanced use of L1 in class
Why your students speak L1 in class (and what to do about it)
15 ways of limiting L1 in class – LINK FIXED
Oh, and Merry Xmas btw (we flew back to Korea on Boxing Day, so despite the snow I’d almost forgotten that it is still that time of year…)
TEFLtastic 
I’ve said this before, but I tend to think teachers start with their own L1 language ability and work backwards. If you cannot speak the local lingo, you’ll be able to find research which indicates an English only environment is the most conducive to language acquisition.
Personally, I think it’s better to know a lot but use a little…. of course, we are talking about a monolingual classroom here. There are obvious practical limitations in the ‘ESL’ classroom.
And a Merry Christmas to you too!
Hmmm, not convinced by that explanation, although obviously knowing none would stop you. For example, I seem to be keener on Japanese than you but have never ever used it in class. I’d think that it had more to do with a few experiences of experimenting with it and succeeding or failing, good or bad experiences with it as a student, or reacting against whatever you were doing early in your career.
I’m not saying it’s an absolute, Alex, but I think it stands as a general rule of thumb.
hi,
I’m a teacher trainee in a private high school, in Turkey. Teachers has asked me to help two students in their studies for their exams at school. One of them is new in school; she has come from a public school. The time for English teaching is very limited in public schools and the efficiency is questionable. On the other hand, students who are in private schools are capable of 5 skills in English. This new student was replaced among the ones who are good at in English and she has to reach their level in order to be successful at her exams. Nevertheless, she is incapable of understanding, answering questions. Besides she has lacked of vocabulary. That’s why she feels threatened in a class where English is the only language. She doesn’t want me to teach in English when we study face to face. She asks me to translate every examples and questions. I praise her after every little achievement. Yet, I don’t know what else can I do since she hesitates so much and we have to cover the exam subjects all the time as her teacher wants us to do. Do you have any suggestion?