The answer depend on your perspective. For optimal learning to take place, students in the classroom must have the freedom to experiment, to try out their own hypotheses about language without feeling that their overall competence is being judged in terms of those trials and errors. In the same way that tournament tennis players must, before a tournament, have the freedom to practice their skill with no implications for their final placement on that day of days, so also must learners have ample opportunities to "play" with language in a classroom without being formally graded. Teaching sets up the practice games of language learning: the opportunities for learners to listen, think, take risks, set goals, and process feedback from the "coach" and then recycle through the skills that they are trying to master.