Language teaching may never produce second language fluency in the classroom among some students. Inability to teach may be more relevant to this failure than inability to learn, as serious efforts by teachers to achieve student fluency may overlook and fail to address the student's problems and obstacles. However, there are limits of second language teaching that can not be overcome. Second language teaching cannot assure that the language is spoken by the student outside the classroom, nor can it assure that the second language spoken to the student outside will be standard. In fact, the second language as taught may not correspond to its common, everyday usage, due to social prejudice and an unwillingness to recognize popular speech. On the other hand there may be pressure on the student outside of school, especially if he speaks an indigenous mother tongue in an inward-looking community, not to use the second language at all. In addition, evidence suggests that learning of any language after the age of 11 years is considerably more stilted and in fact uses a different part of the brain than language learning before that age. Meanwhile, very few educational systems provide for much language teaching at the primary school stage.