<P> In this subject, together with the acquisition of basic knowledge that allow to act with criteria, it is essential the personal exercise. This can not be replaced, nor the time needed to acquire the skill can be shortened. Therefore it is necessary to respect the time programmed for this activity. In fact, the number of hours indicated is the minimum that is considered essential. Given the importance of order and continuity in work, the teacher can be consulted on the approach and distribution of available time. </ P>