In an email I received yesterday the phrase “I teach school” appeared. Although I understand what it means, it sounds a bit strange to me. I suppose it’s a difference between American English and British English.

If I were a teacher, I might say that “I teach in/at a school”, “I’m a teacher” or just “I teach”, but not “I teach school” – that sounds to me like I teach a subject called ‘school’. You could also say “I teach languages/music/physics/[insert name of subject]” or “I teach school children [subject]”.

Would American English speakers, of speakers of other flavours of English, say “I teach college”, “I teach university” or “I teach kindergarten”, or is this structure just used with school? Is it used only in informal writing/speech, or also in formal writing/speech?