Why isn't Japanese needed as an English teacher?

Question:

If, for example, I go to Japan to teach English, why don't I need any Japanese skill? If I'm explaining what an English word means, how do I explain it to them?

Answer:

Actually, it depends on your teaching situation.

If you are an ALT in a school (say a high school of a junior high school) you will be working with Japanese teachers of English, and they will generally be the ones explaining the grammar. You won't have to explain it at all, and if you do they will probably want you to do it in English.

If you're at an eikaiwa, many eikaiwa don't want you to use Japanese in the classroom at all, and they figure that the easiest way to accomplish that is to just have teachers who can't speak Japanese. (Incidentally, it is actually possible to learn a language with little or no explicit grammar instruction in your own language -- many immersion programs work on this sort of target-language-only model.)

If you want to teach at a university (or find some way to be a regular, non-ALT English teacher), you will need to have proficiency in Japanese, but it may not be related to your actual teaching.

Regardless of what kind of job you want, I suggest that you learn Japanese anyway. Even if you never use a word of it in your job, every word you can speak, read, write, and/or understand when you hear will make your daily life in Japan that much easier.