I have found that the only English concept to be irrelevant when teaching elementary school kids. The kids learn just as quickly in either environment. The kids that respond well to an all English environment function just as well when their native language is included sometimes, and the kids that struggle in the all English environment obviously are happier when some explanations are in their native language. The key is to keep the class fun, and all the students will learn at their own pace.

I know this goes contrary to prevailing opinion, but I have personally seen no benefits for the students from using an all English classroom, for students up to age 8 or 9. After that, the benefits do increase, but only minimally, especially when you are teaching alone in a class of over 30 students, the negative effects of classroom chaos can overwhelm the teacher and the students.

I am frankly tired of this all English classroom argument. It certainly didn't help me to learn a foreign language to be stuck in a classroom with only that language. What helped me more was to be able to get instant, solid feedback, which doesn't happen in an all English classroom.