Complex sentence: Internal assessment varies by subject (there may be oral presentations, practical work, or written works) and in most cases is initially graded by the classroom teacher, whose grades are then verified or modified, as necessary, by an appointed, external moderator.
Split into simpler sentences: Internal assessment varies by subject: there may be oral presentations, practical work, or written work. In most cases, these are initially graded by the classroom teacher, whose grades are then verified or modified, as necessary, by an appointed external moderator.