I used to teach 100%, but now teach about 99% of my class in English. So basically, I agree with you. Especially for kids over 3rd grade. You and the research are very correct in the assumption that an all English class is the only way to go, most of the time. But to assume that all English will work 100% of the time is the same as Monbusho hiring only non native speakers for 50 years assuming students would be able to learn English well. They also had research to prove their approach would work. As with anything else in life, a balanced approach is the best approach.
For some kids, especially younger ones, communication is the most important point. If that communication is sometimes in their native language, and that stimulates their interest in you, English, and multicultural experience, I believe that is much more important that than sticking to a hard pedagogial rule.
Children are very flexible, as you have mentioned. So flexible, in fact, that if you tell them that today is an all English day, they will respond in kind. In fact, if they catch me using their native language, they get bonus points. (A great way to enforce all English days!)
My data? Nothing scientific. Enrollment in my after school English club is up over 300% since I joined the school. The previous teacher was an all English proponent. Granted, other factors are much more important in that statistic. 2nd, the mention of English in the kid's diaries in my classes is much, much greater than a coworker's classes who uses English only, all the time.
Don't get me wrong. I agree with you 99% of the time. But there is a time and a place for the students native language in the classroom. It isn't a large amount of time, maybe only 1%. But like you said, the students are flexible, and in my experience, can even understand way I sometimes use their native language--which is to improve the experience for children at risk of being left behind.
I apologize for that first post. It was hasty and harsh.
I really like your statement "it is not what, but how that matters." That is exactly why I teach the way I do. That is why I responded to your post in the first place.
Again, I am sorry and a little embarrassed at coming on so strong in that first post, especially considering I generally agree with you. I could delete, but I will leave it there as punishment to myself. Two more Dohs
Have a great day!
edited for spelling