Quality supervisory practice and effective supervisory systems account for each of these purposes. Indeed a supervisory system based on only one of these purposes is not likely to be successful over time. Focusing only on quality control invites problems from teachers and must be balanced with needed expansive qualities. At the same time, professional development and increased motivation and commitment are too important to overlook.
Indeed one cannot have quality schooling without them. Nonetheless a supervisory system concerned solely with providing support and help to teachers (and thus, by omission, neglecting teaching inadequacies and instances where overriding purposes and defining platforms are ignored) is also inadequate.
Though quality control and teacher improvement are the basic purposes which should drive any system of supervision and evaluation, teacher motivation and commitment may, in the long run, be the most powerful ingredient in building quality schooling. Overwhelming evidence exists which suggests that “knowledge of results” is an 'important ingredient in increasing a person’s motivation to work and in building commitment and loyalty to one’s job.