Training commences by working a small portion of a normal timetable (around 30%), and this gradually builds up over the year to 90% in the third term. The GTP will be supernumerary (in all but a very few exceptional circumstances), which means that qualified teachers must already be employed by the school to teach the classes allocated to the student. School policy varies on how day-to-day teaching by the student is allowed. Some schools will leave students to teach whole classes from the outset, supervised at a distance by the qualified teacher whose class it is and by the school-based mentor and senior tutor. Some schools will insist that the student only 'team-teach' with the qualified teacher present at all times until it is felt the student can cope on his or her own.